20657979 has 18 divisors (see below), whose sum is σ = 31200260. Its totient is φ = 13170168.

The previous prime is 20657929. The next prime is 20657983. The reversal of 20657979 is 97975602.

20657979 is a `hidden beast` number, since 2 + 0 + 6 + 579 + 79 = 666.

It is not a de Polignac number, because 20657979 - 2¹¹ = 20655931 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20657929) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 2592 + ... + 6930.

Almost surely, 2^20657979 is an apocalyptic number.

20657979 is a deficient number, since it is larger than the sum of its proper divisors (10542281).

20657979 is a wasteful number, since it uses less digits than its factorization.

20657979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4391 (or 4365 counting only the distinct ones).

The product of its (nonzero) digits is 238140, while the sum is 45.

The square root of 20657979 is about 4545.1049492833. The cubic root of 20657979 is about 274.3864182164.

It can be divided in two parts, 206 and 57979, that added together give a palindrome (58185).

The spelling of 20657979 in words is "twenty million, six hundred fifty-seven thousand, nine hundred seventy-nine".