21328880 has 40 divisors (see below), whose sum is σ = 52510032. Its totient is φ = 8029184.

The previous prime is 21328873. The next prime is 21328907. The reversal of 21328880 is 8882312.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×21328880² = 909842244108800, which contains 22 as substring.

It is a congruent 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, 6482 + ... + 9201.

Almost surely, 2^21328880 is an apocalyptic number.

21328880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21328880 is an abundant number, since it is smaller than the sum of its proper divisors (31181152).

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

21328880 is a wasteful number, since it uses less digits than its factorization.

21328880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15713 (or 15707 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 32.

The square root of 21328880 is about 4618.3200408807. The cubic root of 21328880 is about 277.3252098418.

The spelling of 21328880 in words is "twenty-one million, three hundred twenty-eight thousand, eight hundred eighty".