21079680 has 64 divisors (see below), whose sum is σ = 67197600. Its totient is φ = 5620736.

The previous prime is 21079673. The next prime is 21079691. The reversal of 21079680 is 8697012.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3570 + ... + 7409.

Almost surely, 2^21079680 is an apocalyptic number.

21079680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21079680 is an abundant number, since it is smaller than the sum of its proper divisors (46117920).

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

21079680 is a wasteful number, since it uses less digits than its factorization.

21079680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11001 (or 10989 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 21079680 is about 4591.2612646200. The cubic root of 21079680 is about 276.2409154619.

The spelling of 21079680 in words is "twenty-one million, seventy-nine thousand, six hundred eighty".