161904921 has 8 divisors (see below), whose sum is σ = 218913984. Its totient is φ = 106416240.

The previous prime is 161904907. The next prime is 161904929. The reversal of 161904921 is 129409161.

161904921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161904921 - 2⁷ = 161904793 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (161904929) 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, 379846 + ... + 380271.

It is an arithmetic number, because the mean of its divisors is an integer number (27364248).

Almost surely, 2^161904921 is an apocalyptic number.

It is an amenable number.

161904921 is a deficient number, since it is larger than the sum of its proper divisors (57009063).

161904921 is an equidigital number, since it uses as much as digits as its factorization.

161904921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 760191.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 161904921 is about 12724.1864572946. The cubic root of 161904921 is about 545.0295088250.

The spelling of 161904921 in words is "one hundred sixty-one million, nine hundred four thousand, nine hundred twenty-one".