21172896 has 36 divisors (see below), whose sum is σ = 60211242. Its totient is φ = 7057536.

The previous prime is 21172891. The next prime is 21172913. The reversal of 21172896 is 69827112.

It can be written as a sum of positive squares in only one way, i.e., 13220496 + 7952400 = 3636^2 + 2820^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21172896.

It is not an unprimeable number, because it can be changed into a prime (21172891) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36471 + ... + 37046.

Almost surely, 2^21172896 is an apocalyptic number.

It is an amenable number.

21172896 is an abundant number, since it is smaller than the sum of its proper divisors (39038346).

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

21172896 is a wasteful number, since it uses less digits than its factorization.

21172896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73533 (or 73522 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21172896 is about 4601.4015256224. The cubic root of 21172896 is about 276.6475030677.

The spelling of 21172896 in words is "twenty-one million, one hundred seventy-two thousand, eight hundred ninety-six".