20856165 has 24 divisors (see below), whose sum is σ = 36682464. Its totient is φ = 10111200.

The previous prime is 20856131. The next prime is 20856181. The reversal of 20856165 is 56165802.

It is not a de Polignac number, because 20856165 - 2⁸ = 20855909 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3931 + ... + 7560.

It is an arithmetic number, because the mean of its divisors is an integer number (1528436).

Almost surely, 2^20856165 is an apocalyptic number.

It is an amenable number.

20856165 is a deficient number, since it is larger than the sum of its proper divisors (15826299).

20856165 is a wasteful number, since it uses less digits than its factorization.

20856165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11521 (or 11510 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 33.

The square root of 20856165 is about 4566.8550447764. The cubic root of 20856165 is about 275.2610853801.

The spelling of 20856165 in words is "twenty million, eight hundred fifty-six thousand, one hundred sixty-five".