21688580 has 12 divisors (see below), whose sum is σ = 45546060. Its totient is φ = 8675424.

The previous prime is 21688571. The next prime is 21688603. The reversal of 21688580 is 8588612.

It can be written as a sum of positive squares in 2 ways, for example, as 10982596 + 10705984 = 3314^2 + 3272^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 542195 + ... + 542234.

It is an arithmetic number, because the mean of its divisors is an integer number (3795505).

Almost surely, 2^21688580 is an apocalyptic number.

21688580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21688580 is an abundant number, since it is smaller than the sum of its proper divisors (23857480).

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

21688580 is a wasteful number, since it uses less digits than its factorization.

21688580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1084438 (or 1084436 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 38.

The square root of 21688580 is about 4657.0999559812. The cubic root of 21688580 is about 278.8755070365.

The spelling of 21688580 in words is "twenty-one million, six hundred eighty-eight thousand, five hundred eighty".