20856713 has 4 divisors (see below), whose sum is σ = 21575940. Its totient is φ = 20137488.

The previous prime is 20856709. The next prime is 20856721. The reversal of 20856713 is 31765802.

It is a happy number.

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 16908544 + 3948169 = 4112^2 + 1987^2 .

It is a cyclic number.

It is not a de Polignac number, because 20856713 - 2² = 20856709 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20856713.

It is not an unprimeable number, because it can be changed into a prime (20856733) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 359570 + ... + 359627.

It is an arithmetic number, because the mean of its divisors is an integer number (5393985).

Almost surely, 2^20856713 is an apocalyptic number.

It is an amenable number.

20856713 is a deficient number, since it is larger than the sum of its proper divisors (719227).

20856713 is an equidigital number, since it uses as much as digits as its factorization.

20856713 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 719226.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 20856713 is about 4566.9150419074. The cubic root of 20856713 is about 275.2634962061.

The spelling of 20856713 in words is "twenty million, eight hundred fifty-six thousand, seven hundred thirteen".