21667880 has 32 divisors (see below), whose sum is σ = 52504200. Its totient is φ = 8000256.

The previous prime is 21667879. The next prime is 21667913. The reversal of 21667880 is 8876612.

It can be written as a sum of positive squares in 4 ways, for example, as 9375844 + 12292036 = 3062^2 + 3506^2 .

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, 20315 + ... + 21354.

Almost surely, 2^21667880 is an apocalyptic number.

21667880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21667880 is an abundant number, since it is smaller than the sum of its proper divisors (30836320).

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

21667880 is a wasteful number, since it uses less digits than its factorization.

21667880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41693 (or 41689 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 21667880 is about 4654.8770123388. The cubic root of 21667880 is about 278.7867574042.

The spelling of 21667880 in words is "twenty-one million, six hundred sixty-seven thousand, eight hundred eighty".