20659639 has 16 divisors (see below), whose sum is σ = 27740160. Its totient is φ = 14859360.

The previous prime is 20659627. The next prime is 20659697. The reversal of 20659639 is 93695602.

It is a cyclic number.

It is not a de Polignac number, because 20659639 - 2⁹ = 20659127 is a prime.

It is a super-2 number, since 2×20659639² = 853641367220642, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20659619) by changing a digit.

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, 9319 + ... + 11320.

It is an arithmetic number, because the mean of its divisors is an integer number (1733760).

Almost surely, 2^20659639 is an apocalyptic number.

20659639 is a deficient number, since it is larger than the sum of its proper divisors (7080521).

20659639 is a wasteful number, since it uses less digits than its factorization.

20659639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20670.

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

The square root of 20659639 is about 4545.2875596600. The cubic root of 20659639 is about 274.3937675842.

The spelling of 20659639 in words is "twenty million, six hundred fifty-nine thousand, six hundred thirty-nine".