21065660 has 48 divisors (see below), whose sum is σ = 55157760. Its totient is φ = 6565440.

The previous prime is 21065641. The next prime is 21065701. The reversal of 21065660 is 6656012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5300 + ... + 8379.

It is an arithmetic number, because the mean of its divisors is an integer number (1149120).

Almost surely, 2^21065660 is an apocalyptic number.

21065660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21065660 is an abundant number, since it is smaller than the sum of its proper divisors (34092100).

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

21065660 is a wasteful number, since it uses less digits than its factorization.

21065660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13706 (or 13704 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 21065660 is about 4589.7341970968. The cubic root of 21065660 is about 276.1796596844.

The spelling of 21065660 in words is "twenty-one million, sixty-five thousand, six hundred sixty".