18231478981 has 8 divisors (see below), whose sum is σ = 18865863000. Its totient is φ = 17597475840.

The previous prime is 18231478973. The next prime is 18231479017. The reversal of 18231478981 is 18987413281.

It can be written as a sum of positive squares in 4 ways, for example, as 2291153956 + 15940325025 = 47866^2 + 126255^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18231478981 - 2³ = 18231478973 is a prime.

It is a super-2 number, since 2×18231478981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18231478381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3945 + ... + 190993.

It is an arithmetic number, because the mean of its divisors is an integer number (2358232875).

Almost surely, 2^18231478981 is an apocalyptic number.

It is an amenable number.

18231478981 is a deficient number, since it is larger than the sum of its proper divisors (634384019).

18231478981 is a wasteful number, since it uses less digits than its factorization.

18231478981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190439.

The product of its digits is 774144, while the sum is 52.

The spelling of 18231478981 in words is "eighteen billion, two hundred thirty-one million, four hundred seventy-eight thousand, nine hundred eighty-one".