18648313991 has 4 divisors (see below), whose sum is σ = 18651155952. Its totient is φ = 18645472032.

The previous prime is 18648313987. The next prime is 18648314053. The reversal of 18648313991 is 19931384681.

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

It is a cyclic number.

It is not a de Polignac number, because 18648313991 - 2² = 18648313987 is a prime.

It is a super-2 number, since 2×18648313991² (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 (18648313391) 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, 1411115 + ... + 1424268.

It is an arithmetic number, because the mean of its divisors is an integer number (4662788988).

Almost surely, 2^18648313991 is an apocalyptic number.

18648313991 is a deficient number, since it is larger than the sum of its proper divisors (2841961).

18648313991 is an equidigital number, since it uses as much as digits as its factorization.

18648313991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2841960.

The product of its digits is 1119744, while the sum is 53.

The spelling of 18648313991 in words is "eighteen billion, six hundred forty-eight million, three hundred thirteen thousand, nine hundred ninety-one".