21244928 has 22 divisors (see below), whose sum is σ = 42471156. Its totient is φ = 10621952.

The previous prime is 21244921. The next prime is 21244969. The reversal of 21244928 is 82944212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 21244894 and 21244903.

It is not an unprimeable number, because it can be changed into a prime (21244921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9350 + ... + 11397.

Almost surely, 2^21244928 is an apocalyptic number.

It is an amenable number.

21244928 is a deficient number, since it is larger than the sum of its proper divisors (21226228).

21244928 is an equidigital number, since it uses as much as digits as its factorization.

21244928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20767 (or 20749 counting only the distinct ones).

The product of its digits is 9216, while the sum is 32.

The square root of 21244928 is about 4609.2220601746. Note that the first 3 decimals coincide. The cubic root of 21244928 is about 276.9608741064.

The spelling of 21244928 in words is "twenty-one million, two hundred forty-four thousand, nine hundred twenty-eight".