161991524 has 24 divisors (see below), whose sum is σ = 286441848. Its totient is φ = 80156160.

The previous prime is 161991517. The next prime is 161991527. The reversal of 161991524 is 425199161.

It can be written as a sum of positive squares in 4 ways, for example, as 47886400 + 114105124 = 6920^2 + 10682^2 .

It is not an unprimeable number, because it can be changed into a prime (161991527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 189482 + ... + 190334.

It is an arithmetic number, because the mean of its divisors is an integer number (11935077).

Almost surely, 2^161991524 is an apocalyptic number.

It is an amenable number.

161991524 is a deficient number, since it is larger than the sum of its proper divisors (124450324).

161991524 is a wasteful number, since it uses less digits than its factorization.

161991524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1295 (or 1293 counting only the distinct ones).

The product of its digits is 19440, while the sum is 38.

The square root of 161991524 is about 12727.5890882759. The cubic root of 161991524 is about 545.1266703294.

The spelling of 161991524 in words is "one hundred sixty-one million, nine hundred ninety-one thousand, five hundred twenty-four".