166126321 has 3 divisors (see below), whose sum is σ = 166139211. Its totient is φ = 166113432.

The previous prime is 166126307. The next prime is 166126333. The reversal of 166126321 is 123621661.

The square root of 166126321 is 12889.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 123621661 = 113 ⋅1093997.

It can be written as a sum of positive squares in only one way, i.e., 108972721 + 57153600 = 10439^2 + 7560^2 .

It is not a de Polignac number, because 166126321 - 2²⁵ = 132571889 is a prime.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 166126321.

It is not an unprimeable number, because it can be changed into a prime (166126351) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 6445 + ... + 19333.

It is an arithmetic number, because the mean of its divisors is an integer number (55379737).

Almost surely, 2^166126321 is an apocalyptic number.

166126321 is the 12889-th square number.

166126321 is the 6445-th centered octagonal number.

It is an amenable number.

166126321 is a deficient number, since it is larger than the sum of its proper divisors (12890).

166126321 is an frugal number, since it uses more digits than its factorization.

166126321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25778 (or 12889 counting only the distinct ones).

The product of its digits is 2592, while the sum is 28.

The cubic root of 166126321 is about 549.7258369121.

Adding to 166126321 its reverse (123621661), we get a palindrome (289747982).

The spelling of 166126321 in words is "one hundred sixty-six million, one hundred twenty-six thousand, three hundred twenty-one".