18718617856 has 81 divisors (see below), whose sum is σ = 39770358901. Its totient is φ = 8791248896.

The previous prime is 18718617823. The next prime is 18718617859. The reversal of 18718617856 is 65871681781.

The square root of 18718617856 is 136816.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 14573318400 + 4145299456 = 120720^2 + 64384^2 .

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18718617856.

It is not an unprimeable number, because it can be changed into a prime (18718617859) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 37213701 + ... + 37214203.

Almost surely, 2^18718617856 is an apocalyptic number.

18718617856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

18718617856 is the 136816-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18718617856

18718617856 is an abundant number, since it is smaller than the sum of its proper divisors (21051741045).

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

18718617856 is an frugal number, since it uses more digits than its factorization.

18718617856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1056 (or 522 counting only the distinct ones).

The product of its digits is 4515840, while the sum is 58.

The spelling of 18718617856 in words is "eighteen billion, seven hundred eighteen million, six hundred seventeen thousand, eight hundred fifty-six".