21667660 has 24 divisors (see below), whose sum is σ = 52002720. Its totient is φ = 7428864.

The previous prime is 21667651. The next prime is 21667703. The reversal of 21667660 is 6676612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77245 + ... + 77524.

It is an arithmetic number, because the mean of its divisors is an integer number (2166780).

Almost surely, 2^21667660 is an apocalyptic number.

21667660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21667660 is an abundant number, since it is smaller than the sum of its proper divisors (30335060).

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

21667660 is a wasteful number, since it uses less digits than its factorization.

21667660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154785 (or 154783 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 34.

The square root of 21667660 is about 4654.8533811496. The cubic root of 21667660 is about 278.7858138679.

It can be divided in two parts, 216 and 67660, that added together give a palindrome (67876).

The spelling of 21667660 in words is "twenty-one million, six hundred sixty-seven thousand, six hundred sixty".