167821 has 4 divisors (see below), whose sum is σ = 168732. Its totient is φ = 166912.

The previous prime is 167809. The next prime is 167861. The reversal of 167821 is 128761.

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.

It can be written as a sum of positive squares in 2 ways, for example, as 114921 + 52900 = 339^2 + 230^2 .

It is a cyclic number.

It is not a de Polignac number, because 167821 - 2⁹ = 167309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (167801) 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, 70 + ... + 583.

It is an arithmetic number, because the mean of its divisors is an integer number (42183).

2¹⁶⁷⁸²¹ is an apocalyptic number.

It is an amenable number.

167821 is a deficient number, since it is larger than the sum of its proper divisors (911).

167821 is an equidigital number, since it uses as much as digits as its factorization.

167821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 910.

The product of its digits is 672, while the sum is 25.

The square root of 167821 is about 409.6596148023. The cubic root of 167821 is about 55.1588794433.

Subtracting from 167821 its reverse (128761), we obtain a triangular number (39060 = T₂₇₉).

The spelling of 167821 in words is "one hundred sixty-seven thousand, eight hundred twenty-one".