21079965 has 16 divisors (see below), whose sum is σ = 34156800. Its totient is φ = 11099712.

The previous prime is 21079931. The next prime is 21079979. The reversal of 21079965 is 56997012.

It is not a de Polignac number, because 21079965 - 2¹³ = 21071773 is a prime.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 7710 + ... + 10079.

It is an arithmetic number, because the mean of its divisors is an integer number (2134800).

Almost surely, 2^21079965 is an apocalyptic number.

It is an amenable number.

21079965 is a deficient number, since it is larger than the sum of its proper divisors (13076835).

21079965 is a wasteful number, since it uses less digits than its factorization.

21079965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17876.

The product of its (nonzero) digits is 34020, while the sum is 39.

The square root of 21079965 is about 4591.2923017382. The cubic root of 21079965 is about 276.2421603939.

The spelling of 21079965 in words is "twenty-one million, seventy-nine thousand, nine hundred sixty-five".