21628580 has 12 divisors (see below), whose sum is σ = 45420060. Its totient is φ = 8651424.

The previous prime is 21628567. The next prime is 21628583. The reversal of 21628580 is 8582612.

It can be written as a sum of positive squares in 2 ways, for example, as 8726116 + 12902464 = 2954^2 + 3592^2 .

It is a hoax number, since the sum of its digits (32) 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 (21628583) 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, 540695 + ... + 540734.

It is an arithmetic number, because the mean of its divisors is an integer number (3785005).

Almost surely, 2^21628580 is an apocalyptic number.

21628580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21628580 is an abundant number, since it is smaller than the sum of its proper divisors (23791480).

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

21628580 is a wasteful number, since it uses less digits than its factorization.

21628580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1081438 (or 1081436 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 21628580 is about 4650.6537174896. The cubic root of 21628580 is about 278.6181060758.

The spelling of 21628580 in words is "twenty-one million, six hundred twenty-eight thousand, five hundred eighty".