21979065 has 16 divisors (see below), whose sum is σ = 35480448. Its totient is φ = 11617536.

The previous prime is 21979043. The next prime is 21979081. The reversal of 21979065 is 56097912.

It is not a de Polignac number, because 21979065 - 2⁹ = 21978553 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4789 + ... + 8178.

It is an arithmetic number, because the mean of its divisors is an integer number (2217528).

Almost surely, 2^21979065 is an apocalyptic number.

It is an amenable number.

21979065 is a deficient number, since it is larger than the sum of its proper divisors (13501383).

21979065 is a wasteful number, since it uses less digits than its factorization.

21979065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13088.

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

The square root of 21979065 is about 4688.1835501610. The cubic root of 21979065 is about 280.1150250197.

The spelling of 21979065 in words is "twenty-one million, nine hundred seventy-nine thousand, sixty-five".