21633680 has 20 divisors (see below), whose sum is σ = 50298492. Its totient is φ = 8653440.

The previous prime is 21633679. The next prime is 21633683. The reversal of 21633680 is 8633612.

It can be written as a sum of positive squares in 2 ways, for example, as 9909904 + 11723776 = 3148^2 + 3424^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×21633680² = 936032220684800, which contains 22 as substring.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21633683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135131 + ... + 135290.

Almost surely, 2^21633680 is an apocalyptic number.

21633680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21633680 is an abundant number, since it is smaller than the sum of its proper divisors (28664812).

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

21633680 is a wasteful number, since it uses less digits than its factorization.

21633680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270434 (or 270428 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 21633680 is about 4651.2019951836. The cubic root of 21633680 is about 278.6400036556.

The spelling of 21633680 in words is "twenty-one million, six hundred thirty-three thousand, six hundred eighty".