18720864 has 36 divisors (see below), whose sum is σ = 53238276. Its totient is φ = 6240192.

The previous prime is 18720847. The next prime is 18720881. The reversal of 18720864 is 46802781.

It is an interprime number because it is at equal distance from previous prime (18720847) and next prime (18720881).

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32214 + ... + 32789.

It is an arithmetic number, because the mean of its divisors is an integer number (1478841).

Almost surely, 2^18720864 is an apocalyptic number.

It is an amenable number.

18720864 is an abundant number, since it is smaller than the sum of its proper divisors (34517412).

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

18720864 is a wasteful number, since it uses less digits than its factorization.

18720864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65019 (or 65008 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 18720864 is about 4326.7613754401. The cubic root of 18720864 is about 265.5269637569.

The spelling of 18720864 in words is "eighteen million, seven hundred twenty thousand, eight hundred sixty-four".