21804560 has 40 divisors (see below), whose sum is σ = 50996736. Its totient is φ = 8670080.

The previous prime is 21804539. The next prime is 21804623. The reversal of 21804560 is 6540812.

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

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, 14567 + ... + 15993.

Almost surely, 2^21804560 is an apocalyptic number.

21804560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21804560 is an abundant number, since it is smaller than the sum of its proper divisors (29192176).

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

21804560 is a wasteful number, since it uses less digits than its factorization.

21804560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1631 (or 1625 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 21804560 is about 4669.5353087861. The cubic root of 21804560 is about 279.3717205380.

The spelling of 21804560 in words is "twenty-one million, eight hundred four thousand, five hundred sixty".