20712865 has 4 divisors (see below), whose sum is σ = 24855444. Its totient is φ = 16570288.

The previous prime is 20712847. The next prime is 20712871. The reversal of 20712865 is 56821702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8202496 + 12510369 = 2864^2 + 3537^2 .

It is a cyclic number.

It is not a de Polignac number, because 20712865 - 2⁹ = 20712353 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2071282 + ... + 2071291.

It is an arithmetic number, because the mean of its divisors is an integer number (6213861).

Almost surely, 2^20712865 is an apocalyptic number.

It is an amenable number.

20712865 is a deficient number, since it is larger than the sum of its proper divisors (4142579).

20712865 is an equidigital number, since it uses as much as digits as its factorization.

20712865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4142578.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 20712865 is about 4551.1388684592. The cubic root of 20712865 is about 274.6292082627.

The spelling of 20712865 in words is "twenty million, seven hundred twelve thousand, eight hundred sixty-five".