81533831218 has 16 divisors (see below), whose sum is σ = 141858437184. Its totient is φ = 34421531760.

The previous prime is 81533831201. The next prime is 81533831219. The reversal of 81533831218 is 81213833518.

It is a super-2 number, since 2×81533831218² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81533831219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43460593 + ... + 43462468.

It is an arithmetic number, because the mean of its divisors is an integer number (8866152324).

Almost surely, 2^81533831218 is an apocalyptic number.

81533831218 is a deficient number, since it is larger than the sum of its proper divisors (60324605966).

81533831218 is a wasteful number, since it uses less digits than its factorization.

81533831218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86923137.

The product of its digits is 138240, while the sum is 43.

The spelling of 81533831218 in words is "eighty-one billion, five hundred thirty-three million, eight hundred thirty-one thousand, two hundred eighteen".