21204880 has 40 divisors (see below), whose sum is σ = 49499064. Its totient is φ = 8448000.

The previous prime is 21204871. The next prime is 21204889. The reversal of 21204880 is 8840212.

It is an interprime number because it is at equal distance from previous prime (21204871) and next prime (21204889).

It can be written as a sum of positive squares in 4 ways, for example, as 11370384 + 9834496 = 3372^2 + 3136^2 .

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

It is a hoax number, since the sum of its digits (25) 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 (21204889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31750 + ... + 32410.

Almost surely, 2^21204880 is an apocalyptic number.

21204880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21204880 is an abundant number, since it is smaller than the sum of its proper divisors (28294184).

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

21204880 is a wasteful number, since it uses less digits than its factorization.

21204880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075 (or 1069 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 25.

The square root of 21204880 is about 4604.8756769320. The cubic root of 21204880 is about 276.7867351947.

The spelling of 21204880 in words is "twenty-one million, two hundred four thousand, eight hundred eighty".