18720756 has 18 divisors (see below), whose sum is σ = 47322002. Its totient is φ = 6240240.

The previous prime is 18720739. The next prime is 18720761. The reversal of 18720756 is 65702781.

It can be written as a sum of positive squares in only one way, i.e., 10112400 + 8608356 = 3180^2 + 2934^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 520021 = 18720756 / (1 + 8 + 7 + 2 + 0 + 7 + 5 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 18720756.

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, 259975 + ... + 260046.

Almost surely, 2^18720756 is an apocalyptic number.

It is an amenable number.

18720756 is an abundant number, since it is smaller than the sum of its proper divisors (28601246).

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

18720756 is a wasteful number, since it uses less digits than its factorization.

18720756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 520031 (or 520026 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 18720756 is about 4326.7488949557. The cubic root of 18720756 is about 265.5264531507.

The spelling of 18720756 in words is "eighteen million, seven hundred twenty thousand, seven hundred fifty-six".