161520631 has 4 divisors (see below), whose sum is σ = 161619192. Its totient is φ = 161422072.

The previous prime is 161520629. The next prime is 161520637. The reversal of 161520631 is 136025161.

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

It is a cyclic number.

It is not a de Polignac number, because 161520631 - 2¹ = 161520629 is a prime.

It is a super-2 number, since 2×161520631² = 52177828477276322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161520596 and 161520605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161520637) 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, 46780 + ... + 50113.

It is an arithmetic number, because the mean of its divisors is an integer number (40404798).

Almost surely, 2^161520631 is an apocalyptic number.

161520631 is a deficient number, since it is larger than the sum of its proper divisors (98561).

161520631 is an equidigital number, since it uses as much as digits as its factorization.

161520631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98560.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 161520631 is about 12709.0767170554. The cubic root of 161520631 is about 544.5979482922.

Adding to 161520631 its reverse (136025161), we get a palindrome (297545792).

The spelling of 161520631 in words is "one hundred sixty-one million, five hundred twenty thousand, six hundred thirty-one".