21228708 has 24 divisors (see below), whose sum is σ = 49762048. Its totient is φ = 7043616.

The previous prime is 21228703. The next prime is 21228709. The reversal of 21228708 is 80782212.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21228703) 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, 1291 + ... + 6642.

Almost surely, 2^21228708 is an apocalyptic number.

It is an amenable number.

21228708 is an abundant number, since it is smaller than the sum of its proper divisors (28533340).

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

21228708 is a wasteful number, since it uses less digits than its factorization.

21228708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8163 (or 8161 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 21228708 is about 4607.4622082010. The cubic root of 21228708 is about 276.8903718024.

It can be divided in two parts, 212 and 28708, that added together give a triangular number (28920 = T₂₄₀).

The spelling of 21228708 in words is "twenty-one million, two hundred twenty-eight thousand, seven hundred eight".