81799513387 has 4 divisors (see below), whose sum is σ = 82523403000. Its totient is φ = 81075623776.

The previous prime is 81799513379. The next prime is 81799513421. The reversal of 81799513387 is 78331599718.

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 81799513387 - 2³ = 81799513379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81799513307) 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, 361944637 + ... + 361944862.

It is an arithmetic number, because the mean of its divisors is an integer number (20630850750).

Almost surely, 2^81799513387 is an apocalyptic number.

81799513387 is a deficient number, since it is larger than the sum of its proper divisors (723889613).

81799513387 is a wasteful number, since it uses less digits than its factorization.

81799513387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723889612.

The product of its digits is 11430720, while the sum is 61.

The spelling of 81799513387 in words is "eighty-one billion, seven hundred ninety-nine million, five hundred thirteen thousand, three hundred eighty-seven".