161904 has 20 divisors (see below), whose sum is σ = 418376. Its totient is φ = 53952.

The previous prime is 161881. The next prime is 161911. The reversal of 161904 is 409161.

It is a hoax number, since the sum of its digits (21) coincides with the sum of the digits of its distinct prime factors.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1639 + ... + 1734.

2¹⁶¹⁹⁰⁴ is an apocalyptic number.

It is an amenable number.

161904 is an abundant number, since it is smaller than the sum of its proper divisors (256472).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161904 is a wasteful number, since it uses less digits than its factorization.

161904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3384 (or 3378 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 161904 is about 402.3729613182. The cubic root of 161904 is about 54.5028475352.

The spelling of 161904 in words is "one hundred sixty-one thousand, nine hundred four".