20856880 has 80 divisors (see below), whose sum is σ = 53594784. Its totient is φ = 7485440.

The previous prime is 20856877. The next prime is 20856881. The reversal of 20856880 is 8865802.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (20856881) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 120474 + ... + 120646.

Almost surely, 2^20856880 is an apocalyptic number.

20856880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20856880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26797392).

20856880 is an abundant number, since it is smaller than the sum of its proper divisors (32737904).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20856880 is a wasteful number, since it uses less digits than its factorization.

20856880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334 (or 328 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 37.

The square root of 20856880 is about 4566.9333255479. The cubic root of 20856880 is about 275.2642308837.

It can be divided in two parts, 20856 and 880, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 20856880 in words is "twenty million, eight hundred fifty-six thousand, eight hundred eighty".