81387956599 has 4 divisors (see below), whose sum is σ = 81389102200. Its totient is φ = 81386811000.

The previous prime is 81387956591. The next prime is 81387956623. The reversal of 81387956599 is 99565978318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81387956599 - 2³ = 81387956591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81387956591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 458652 + ... + 610849.

It is an arithmetic number, because the mean of its divisors is an integer number (20347275550).

Almost surely, 2^81387956599 is an apocalyptic number.

81387956599 is a deficient number, since it is larger than the sum of its proper divisors (1145601).

81387956599 is a wasteful number, since it uses less digits than its factorization.

81387956599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1145600.

The product of its digits is 146966400, while the sum is 70.

The spelling of 81387956599 in words is "eighty-one billion, three hundred eighty-seven million, nine hundred fifty-six thousand, five hundred ninety-nine".