21567680 has 28 divisors (see below), whose sum is σ = 51358800. Its totient is φ = 8626944.

The previous prime is 21567673. The next prime is 21567691. The reversal of 21567680 is 8676512.

It is a self number, because there is not a number n which added to its sum of digits gives 21567680.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33380 + ... + 34019.

Almost surely, 2^21567680 is an apocalyptic number.

21567680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21567680 is an abundant number, since it is smaller than the sum of its proper divisors (29791120).

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

21567680 is an equidigital number, since it uses as much as digits as its factorization.

21567680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67416 (or 67406 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 21567680 is about 4644.1016354081. The cubic root of 21567680 is about 278.3563568351.

The spelling of 21567680 in words is "twenty-one million, five hundred sixty-seven thousand, six hundred eighty".