18981618864578 has 4 divisors (see below), whose sum is σ = 28472428296870. Its totient is φ = 9490809432288.

The previous prime is 18981618864547. The next prime is 18981618864589. The reversal of 18981618864578 is 87546881618981.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18910435023769 + 71183840809 = 4348613^2 + 266803^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4745404716143 + ... + 4745404716146.

Almost surely, 2^{18981618864578} is an apocalyptic number.

18981618864578 is a deficient number, since it is larger than the sum of its proper divisors (9490809432292).

18981618864578 is an equidigital number, since it uses as much as digits as its factorization.

18981618864578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9490809432291.

The product of its digits is 1486356480, while the sum is 80.

The spelling of 18981618864578 in words is "eighteen trillion, nine hundred eighty-one billion, six hundred eighteen million, eight hundred sixty-four thousand, five hundred seventy-eight".