81015225993 has 24 divisors (see below), whose sum is σ = 133436846088. Its totient is φ = 46922844672.

The previous prime is 81015225953. The next prime is 81015226003. The reversal of 81015225993 is 39952251018.

81015225993 is a `hidden beast` number, since 8 + 1 + 0 + 1 + 52 + 2 + 599 + 3 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 6643391049 + 74371834944 = 81507^2 + 272712^2 .

It is not a de Polignac number, because 81015225993 - 2⁹ = 81015225481 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81015225913) 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 23 ways as a sum of consecutive naturals, for example, 20363830 + ... + 20367807.

It is an arithmetic number, because the mean of its divisors is an integer number (5559868587).

Almost surely, 2^81015225993 is an apocalyptic number.

It is an amenable number.

81015225993 is a deficient number, since it is larger than the sum of its proper divisors (52421620095).

81015225993 is a wasteful number, since it uses less digits than its factorization.

81015225993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40731673 (or 40731670 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The spelling of 81015225993 in words is "eighty-one billion, fifteen million, two hundred twenty-five thousand, nine hundred ninety-three".