161501904 has 80 divisors (see below), whose sum is σ = 490861440. Its totient is φ = 50664960.

The previous prime is 161501861. The next prime is 161501927. The reversal of 161501904 is 409105161.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3652 + ... + 18339.

It is an arithmetic number, because the mean of its divisors is an integer number (6135768).

Almost surely, 2^161501904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161501904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (245430720).

161501904 is an abundant number, since it is smaller than the sum of its proper divisors (329359536).

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

161501904 is a wasteful number, since it uses less digits than its factorization.

161501904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22025 (or 22013 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 161501904 is about 12708.3399387961. The cubic root of 161501904 is about 544.5769002484.

The spelling of 161501904 in words is "one hundred sixty-one million, five hundred one thousand, nine hundred four".