81015225994 has 16 divisors (see below), whose sum is σ = 122196019176. Its totient is φ = 40283409600.

The previous prime is 81015225953. The next prime is 81015226003. The reversal of 81015225994 is 49952251018.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 78840216225 + 2175009769 = 280785^2 + 46637^2 .

It is an unprimeable number.

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, 828784 + ... + 921364.

Almost surely, 2^81015225994 is an apocalyptic number.

81015225994 is a deficient number, since it is larger than the sum of its proper divisors (41180793182).

81015225994 is a wasteful number, since it uses less digits than its factorization.

81015225994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95001.

The product of its (nonzero) digits is 259200, while the sum is 46.

The spelling of 81015225994 in words is "eighty-one billion, fifteen million, two hundred twenty-five thousand, nine hundred ninety-four".