18720856 has 32 divisors (see below), whose sum is σ = 43764480. Its totient is φ = 7293600.

The previous prime is 18720847. The next prime is 18720881. The reversal of 18720856 is 65802781.

It is a congruent number.

It is an unprimeable number.

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, 14580 + ... + 15811.

It is an arithmetic number, because the mean of its divisors is an integer number (1367640).

Almost surely, 2^18720856 is an apocalyptic number.

It is an amenable number.

18720856 is an abundant number, since it is smaller than the sum of its proper divisors (25043624).

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

18720856 is a wasteful number, since it uses less digits than its factorization.

18720856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30415 (or 30411 counting only the distinct ones).

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

The square root of 18720856 is about 4326.7604509610. The cubic root of 18720856 is about 265.5269259343.

The spelling of 18720856 in words is "eighteen million, seven hundred twenty thousand, eight hundred fifty-six".