18820640331 has 8 divisors (see below), whose sum is σ = 27882430160. Its totient is φ = 12547093536.

The previous prime is 18820640329. The next prime is 18820640339. The reversal of 18820640331 is 13304602881.

18820640331 is a `hidden beast` number, since 1 + 8 + 8 + 2 + 0 + 640 + 3 + 3 + 1 = 666.

It is not a de Polignac number, because 18820640331 - 2¹ = 18820640329 is a prime.

It is a super-2 number, since 2×18820640331² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18820640339) 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, 348530350 + ... + 348530403.

It is an arithmetic number, because the mean of its divisors is an integer number (3485303770).

Almost surely, 2^18820640331 is an apocalyptic number.

18820640331 is a deficient number, since it is larger than the sum of its proper divisors (9061789829).

18820640331 is an equidigital number, since it uses as much as digits as its factorization.

18820640331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 697060762 (or 697060756 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The spelling of 18820640331 in words is "eighteen billion, eight hundred twenty million, six hundred forty thousand, three hundred thirty-one".