20856871 has 8 divisors (see below), whose sum is σ = 23997600. Its totient is φ = 17756448.

The previous prime is 20856839. The next prime is 20856877. The reversal of 20856871 is 17865802.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20856871 - 2⁵ = 20856839 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 20856871.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20856877) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 8956 + ... + 11041.

It is an arithmetic number, because the mean of its divisors is an integer number (2999700).

Almost surely, 2^20856871 is an apocalyptic number.

20856871 is a deficient number, since it is larger than the sum of its proper divisors (3140729).

20856871 is a wasteful number, since it uses less digits than its factorization.

20856871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20153.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 20856871 is about 4566.9323402039. The cubic root of 20856871 is about 275.2641912904.

The spelling of 20856871 in words is "twenty million, eight hundred fifty-six thousand, eight hundred seventy-one".