81731319999 has 16 divisors (see below), whose sum is σ = 131097857280. Its totient is φ = 44245526400.

The previous prime is 81731319977. The next prime is 81731320051. The reversal of 81731319999 is 99991313718.

It is not a de Polignac number, because 81731319999 - 2⁷ = 81731319871 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81731319599) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 102419802 + ... + 102420599.

It is an arithmetic number, because the mean of its divisors is an integer number (8193616080).

Almost surely, 2^81731319999 is an apocalyptic number.

81731319999 is a deficient number, since it is larger than the sum of its proper divisors (49366537281).

81731319999 is a wasteful number, since it uses less digits than its factorization.

81731319999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204840430.

The product of its digits is 3306744, while the sum is 60.

The spelling of 81731319999 in words is "eighty-one billion, seven hundred thirty-one million, three hundred nineteen thousand, nine hundred ninety-nine".