161631431 has 6 divisors (see below), whose sum is σ = 175021200. Its totient is φ = 149198088.

The previous prime is 161631409. The next prime is 161631433. The reversal of 161631431 is 134136161.

It is a de Polignac number, because none of the positive numbers 2^k-161631431 is a prime.

It is a super-2 number, since 2×161631431² = 52249438974215522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161631431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161631433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 478031 + ... + 478368.

It is an arithmetic number, because the mean of its divisors is an integer number (29170200).

Almost surely, 2^161631431 is an apocalyptic number.

161631431 is a deficient number, since it is larger than the sum of its proper divisors (13389769).

161631431 is an equidigital number, since it uses as much as digits as its factorization.

161631431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 956425 (or 956412 counting only the distinct ones).

The product of its digits is 1296, while the sum is 26.

The square root of 161631431 is about 12713.4350590232. The cubic root of 161631431 is about 544.7224476825.

Adding to 161631431 its reverse (134136161), we get a palindrome (295767592).

The spelling of 161631431 in words is "one hundred sixty-one million, six hundred thirty-one thousand, four hundred thirty-one".