1818231851538 has 24 divisors (see below), whose sum is σ = 3944876865228. Its totient is φ = 605250434592.

The previous prime is 1818231851519. The next prime is 1818231851561. The reversal of 1818231851538 is 8351581328181.

1818231851538 is a `hidden beast` number, since 1 + 8 + 1 + 8 + 23 + 1 + 85 + 1 + 538 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1817813117169 + 418734369 = 1348263^2 + 20463^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 68890545 + ... + 68916932.

Almost surely, 2^{1818231851538} is an apocalyptic number.

1818231851538 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1818231851538 is an abundant number, since it is smaller than the sum of its proper divisors (2126645013690).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1818231851538 is a wasteful number, since it uses less digits than its factorization.

1818231851538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137808218 (or 137808215 counting only the distinct ones).

The product of its digits is 1843200, while the sum is 54.

The spelling of 1818231851538 in words is "one trillion, eight hundred eighteen billion, two hundred thirty-one million, eight hundred fifty-one thousand, five hundred thirty-eight".