81599401879 has 4 divisors (see below), whose sum is σ = 81601534384. Its totient is φ = 81597269376.

The previous prime is 81599401867. The next prime is 81599401883. The reversal of 81599401879 is 97810499518.

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 81599401879 - 2³⁵ = 47239663511 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 (81599401579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1007787 + ... + 1085740.

It is an arithmetic number, because the mean of its divisors is an integer number (20400383596).

Almost surely, 2^81599401879 is an apocalyptic number.

81599401879 is a deficient number, since it is larger than the sum of its proper divisors (2132505).

81599401879 is a wasteful number, since it uses less digits than its factorization.

81599401879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2132504.

The product of its (nonzero) digits is 6531840, while the sum is 61.

The spelling of 81599401879 in words is "eighty-one billion, five hundred ninety-nine million, four hundred one thousand, eight hundred seventy-nine".