20720856 has 32 divisors (see below), whose sum is σ = 55787760. Its totient is φ = 6375552.

The previous prime is 20720789. The next prime is 20720893. The reversal of 20720856 is 65802702.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32895 + ... + 33518.

Almost surely, 2^20720856 is an apocalyptic number.

20720856 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

20720856 is an abundant number, since it is smaller than the sum of its proper divisors (35066904).

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

20720856 is a wasteful number, since it uses less digits than its factorization.

20720856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66435 (or 66431 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 20720856 is about 4552.0166959272. The cubic root of 20720856 is about 274.6645209350.

The spelling of 20720856 in words is "twenty million, seven hundred twenty thousand, eight hundred fifty-six".