165918631 has 2 divisors, whose sum is σ = 165918632. Its totient is φ = 165918630.

The previous prime is 165918629. The next prime is 165918637. The reversal of 165918631 is 136819561.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 165918631 - 2¹ = 165918629 is a prime.

It is a super-2 number, since 2×165918631² = 55057984225828322, which contains 22 as substring.

Together with 165918629, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165918637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82959315 + 82959316.

It is an arithmetic number, because the mean of its divisors is an integer number (82959316).

Almost surely, 2^165918631 is an apocalyptic number.

165918631 is a deficient number, since it is larger than the sum of its proper divisors (1).

165918631 is an equidigital number, since it uses as much as digits as its factorization.

165918631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 40.

The square root of 165918631 is about 12880.9406100642. The cubic root of 165918631 is about 549.4966535398.

The spelling of 165918631 in words is "one hundred sixty-five million, nine hundred eighteen thousand, six hundred thirty-one".