81339531878 has 16 divisors (see below), whose sum is σ = 138888055296. Its totient is φ = 35365013640.

The previous prime is 81339531857. The next prime is 81339531893. The reversal of 81339531878 is 87813593318.

It is a happy number.

It is a super-2 number, since 2×81339531878² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 80374526 + ... + 80375537.

It is an arithmetic number, because the mean of its divisors is an integer number (8680503456).

Almost surely, 2^81339531878 is an apocalyptic number.

81339531878 is a deficient number, since it is larger than the sum of its proper divisors (57548523418).

81339531878 is a wasteful number, since it uses less digits than its factorization.

81339531878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160750099.

The product of its digits is 4354560, while the sum is 56.

The spelling of 81339531878 in words is "eighty-one billion, three hundred thirty-nine million, five hundred thirty-one thousand, eight hundred seventy-eight".