18113315981 has 4 divisors (see below), whose sum is σ = 18114180000. Its totient is φ = 18112451964.

The previous prime is 18113315977. The next prime is 18113315993. The reversal of 18113315981 is 18951331181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18113315981 - 2² = 18113315977 is a prime.

It is a super-2 number, since 2×18113315981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18113315951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 399761 + ... + 442758.

It is an arithmetic number, because the mean of its divisors is an integer number (4528545000).

Almost surely, 2^18113315981 is an apocalyptic number.

It is an amenable number.

18113315981 is a deficient number, since it is larger than the sum of its proper divisors (864019).

18113315981 is an equidigital number, since it uses as much as digits as its factorization.

18113315981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864018.

The product of its digits is 25920, while the sum is 41.

The spelling of 18113315981 in words is "eighteen billion, one hundred thirteen million, three hundred fifteen thousand, nine hundred eighty-one".