20939665 has 8 divisors (see below), whose sum is σ = 26605800. Its totient is φ = 15766272.

The previous prime is 20939657. The next prime is 20939671. The reversal of 20939665 is 56693902.

It can be written as a sum of positive squares in 4 ways, for example, as 788544 + 20151121 = 888^2 + 4489^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20939665 - 2³ = 20939657 is a prime.

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, 123090 + ... + 123259.

It is an arithmetic number, because the mean of its divisors is an integer number (3325725).

Almost surely, 2^20939665 is an apocalyptic number.

It is an amenable number.

20939665 is a deficient number, since it is larger than the sum of its proper divisors (5666135).

20939665 is a wasteful number, since it uses less digits than its factorization.

20939665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246371.

The product of its (nonzero) digits is 87480, while the sum is 40.

The square root of 20939665 is about 4575.9878714874. The cubic root of 20939665 is about 275.6279424583.

The spelling of 20939665 in words is "twenty million, nine hundred thirty-nine thousand, six hundred sixty-five".