20161904 has 40 divisors (see below), whose sum is σ = 46092288. Its totient is φ = 8360640.

The previous prime is 20161901. The next prime is 20161909. The reversal of 20161904 is 40916102.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 20161904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20161901) 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, 569 + ... + 6375.

Almost surely, 2^20161904 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 20161904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23046144).

20161904 is an abundant number, since it is smaller than the sum of its proper divisors (25930384).

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

20161904 is a wasteful number, since it uses less digits than its factorization.

20161904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5853 (or 5847 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 20161904 is about 4490.2008863747. The cubic root of 20161904 is about 272.1722524844.

The spelling of 20161904 in words is "twenty million, one hundred sixty-one thousand, nine hundred four".