21357028 has 24 divisors (see below), whose sum is σ = 46597824. Its totient is φ = 8320800.

The previous prime is 21356989. The next prime is 21357031. The reversal of 21357028 is 82075312.

It is a super-2 number, since 2×21357028² = 912245289985568, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 21356987 and 21357005.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34363 + ... + 34978.

It is an arithmetic number, because the mean of its divisors is an integer number (1941576).

Almost surely, 2^21357028 is an apocalyptic number.

21357028 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21357028 is an abundant number, since it is smaller than the sum of its proper divisors (25240796).

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

21357028 is a wasteful number, since it uses less digits than its factorization.

21357028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69363 (or 69361 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 21357028 is about 4621.3664645860. The cubic root of 21357028 is about 277.4471527749.

The spelling of 21357028 in words is "twenty-one million, three hundred fifty-seven thousand, twenty-eight".