21808680 has 32 divisors (see below), whose sum is σ = 65426400. Its totient is φ = 5815616.

The previous prime is 21808621. The next prime is 21808681. The reversal of 21808680 is 8680812.

It is not an unprimeable number, because it can be changed into a prime (21808681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 90750 + ... + 90989.

It is an arithmetic number, because the mean of its divisors is an integer number (2044575).

Almost surely, 2^21808680 is an apocalyptic number.

21808680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21808680 is an abundant number, since it is smaller than the sum of its proper divisors (43617720).

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

21808680 is a wasteful number, since it uses less digits than its factorization.

21808680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181753 (or 181749 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 33.

The square root of 21808680 is about 4669.9764453367. The cubic root of 21808680 is about 279.3893153133.

The spelling of 21808680 in words is "twenty-one million, eight hundred eight thousand, six hundred eighty".