21280708 has 12 divisors (see below), whose sum is σ = 37332652. Its totient is φ = 10614240.

The previous prime is 21280691. The next prime is 21280709. The reversal of 21280708 is 80708212.

It can be written as a sum of positive squares in 2 ways, for example, as 777924 + 20502784 = 882^2 + 4528^2 .

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21280709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4635 + ... + 8002.

Almost surely, 2^21280708 is an apocalyptic number.

It is an amenable number.

21280708 is a deficient number, since it is larger than the sum of its proper divisors (16051944).

21280708 is a wasteful number, since it uses less digits than its factorization.

21280708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13062 (or 13060 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 21280708 is about 4613.1017764623. The cubic root of 21280708 is about 277.1162696609.

The spelling of 21280708 in words is "twenty-one million, two hundred eighty thousand, seven hundred eight".