21224920 has 32 divisors (see below), whose sum is σ = 47945520. Its totient is φ = 8456320.

The previous prime is 21224911. The next prime is 21224923. The reversal of 21224920 is 2942212.

It is a junction number, because it is equal to n+sod(n) for n = 21224891 and 21224900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224923) 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, 10815 + ... + 12625.

Almost surely, 2^21224920 is an apocalyptic number.

21224920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21224920 is an abundant number, since it is smaller than the sum of its proper divisors (26720600).

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

21224920 is a wasteful number, since it uses less digits than its factorization.

21224920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2115 (or 2111 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21224920 is about 4607.0511175805. The cubic root of 21224920 is about 276.8739016036.

The spelling of 21224920 in words is "twenty-one million, two hundred twenty-four thousand, nine hundred twenty".