20856663 has 16 divisors (see below), whose sum is σ = 31020000. Its totient is φ = 13849920.

The previous prime is 20856629. The next prime is 20856679. The reversal of 20856663 is 36665802.

It is not a de Polignac number, because 20856663 - 2⁶ = 20856599 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20855663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6213 + ... + 8961.

It is an arithmetic number, because the mean of its divisors is an integer number (1938750).

Almost surely, 2^20856663 is an apocalyptic number.

20856663 is a deficient number, since it is larger than the sum of its proper divisors (10163337).

20856663 is a wasteful number, since it uses less digits than its factorization.

20856663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3039 (or 3033 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 20856663 is about 4566.9095677493. The cubic root of 20856663 is about 275.2632762419.

The spelling of 20856663 in words is "twenty million, eight hundred fifty-six thousand, six hundred sixty-three".