21907228 has 24 divisors (see below), whose sum is σ = 46121600. Its totient is φ = 8894448.

The previous prime is 21907189. The next prime is 21907229. The reversal of 21907228 is 82270912.

It is a self number, because there is not a number n which added to its sum of digits gives 21907228.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21907229) 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, 20058 + ... + 21121.

Almost surely, 2^21907228 is an apocalyptic number.

21907228 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21907228 is an abundant number, since it is smaller than the sum of its proper divisors (24214372).

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

21907228 is a wasteful number, since it uses less digits than its factorization.

21907228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41209 (or 41207 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21907228 is about 4680.5157835435. The cubic root of 21907228 is about 279.8095132966.

The spelling of 21907228 in words is "twenty-one million, nine hundred seven thousand, two hundred twenty-eight".