20972865 has 16 divisors (see below), whose sum is σ = 35323200. Its totient is φ = 10596672.

The previous prime is 20972851. The next prime is 20972867. The reversal of 20972865 is 56827902.

It is a happy number.

It is not a de Polignac number, because 20972865 - 2⁶ = 20972801 is a prime.

It is a super-2 number, since 2×20972865² = 879722132616450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20972867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36510 + ... + 37079.

It is an arithmetic number, because the mean of its divisors is an integer number (2207700).

Almost surely, 2^20972865 is an apocalyptic number.

It is an amenable number.

20972865 is a deficient number, since it is larger than the sum of its proper divisors (14350335).

20972865 is a wasteful number, since it uses less digits than its factorization.

20972865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73616.

The product of its (nonzero) digits is 60480, while the sum is 39.

The square root of 20972865 is about 4579.6140667091. The cubic root of 20972865 is about 275.7735356136.

The spelling of 20972865 in words is "twenty million, nine hundred seventy-two thousand, eight hundred sixty-five".