161209904 has 40 divisors (see below), whose sum is σ = 318073392. Its totient is φ = 79139840.

The previous prime is 161209903. The next prime is 161209907. The reversal of 161209904 is 409902161.

It is not an unprimeable number, because it can be changed into a prime (161209901) 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, 309164 + ... + 309684.

Almost surely, 2^161209904 is an apocalyptic number.

It is an amenable number.

161209904 is a deficient number, since it is larger than the sum of its proper divisors (156863488).

161209904 is a wasteful number, since it uses less digits than its factorization.

161209904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845 (or 839 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 161209904 is about 12696.8462225861. The cubic root of 161209904 is about 544.2484987812.

The spelling of 161209904 in words is "one hundred sixty-one million, two hundred nine thousand, nine hundred four".