66206641 has 4 divisors (see below), whose sum is σ = 66273012. Its totient is φ = 66140272.

The previous prime is 66206639. The next prime is 66206663. The reversal of 66206641 is 14660266.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 27081616 + 39125025 = 5204^2 + 6255^2 .

It is a cyclic number.

It is not a de Polignac number, because 66206641 - 2¹ = 66206639 is a prime.

It is a super-3 number, since 3×66206641³ (a number of 24 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66206741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31666 + ... + 33691.

It is an arithmetic number, because the mean of its divisors is an integer number (16568253).

Almost surely, 2^66206641 is an apocalyptic number.

It is an amenable number.

66206641 is a deficient number, since it is larger than the sum of its proper divisors (66371).

66206641 is a wasteful number, since it uses less digits than its factorization.

66206641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66370.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 66206641 is about 8136.7463399076. The cubic root of 66206641 is about 404.5453232045.

The spelling of 66206641 in words is "sixty-six million, two hundred six thousand, six hundred forty-one".