161721925 has 12 divisors (see below), whose sum is σ = 205200160. Its totient is φ = 126367920.

The previous prime is 161721881. The next prime is 161721929. The reversal of 161721925 is 529127161.

161721925 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 161721925 - 2¹³ = 161713733 is a prime.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161721929) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 74145 + ... + 76294.

Almost surely, 2^161721925 is an apocalyptic number.

It is an amenable number.

161721925 is a deficient number, since it is larger than the sum of its proper divisors (43478235).

161721925 is a wasteful number, since it uses less digits than its factorization.

161721925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150492 (or 150487 counting only the distinct ones).

The product of its digits is 7560, while the sum is 34.

The square root of 161721925 is about 12716.9935519367. The cubic root of 161721925 is about 544.8240882198.

The spelling of 161721925 in words is "one hundred sixty-one million, seven hundred twenty-one thousand, nine hundred twenty-five".