21715880 has 32 divisors (see below), whose sum is σ = 49904640. Its totient is φ = 8500800.

The previous prime is 21715873. The next prime is 21715891. The reversal of 21715880 is 8851712.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3896 + ... + 7655.

It is an arithmetic number, because the mean of its divisors is an integer number (1559520).

Almost surely, 2^21715880 is an apocalyptic number.

21715880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21715880 is an abundant number, since it is smaller than the sum of its proper divisors (28188760).

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

21715880 is a wasteful number, since it uses less digits than its factorization.

21715880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11609 (or 11605 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 21715880 is about 4660.0300428216. The cubic root of 21715880 is about 278.9924673480.

The spelling of 21715880 in words is "twenty-one million, seven hundred fifteen thousand, eight hundred eighty".