161315631 has 10 divisors (see below), whose sum is σ = 240977792. Its totient is φ = 107543700.

The previous prime is 161315593. The next prime is 161315633. The reversal of 161315631 is 136513161.

161315631 is a `hidden beast` number, since 1 + 6 + 13 + 15 + 631 = 666.

It is not a de Polignac number, because 161315631 - 2⁷ = 161315503 is a prime.

It is a super-2 number, since 2×161315631² = 52045465609856322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161315595 and 161315604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161315633) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 995695 + ... + 995856.

Almost surely, 2^161315631 is an apocalyptic number.

161315631 is a deficient number, since it is larger than the sum of its proper divisors (79662161).

161315631 is an equidigital number, since it uses as much as digits as its factorization.

161315631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1991563 (or 1991554 counting only the distinct ones).

The product of its digits is 1620, while the sum is 27.

The square root of 161315631 is about 12701.0090544019. The cubic root of 161315631 is about 544.3674517423.

Adding to 161315631 its reverse (136513161), we get a palindrome (297828792).

The spelling of 161315631 in words is "one hundred sixty-one million, three hundred fifteen thousand, six hundred thirty-one".