81177317493 has 16 divisors (see below), whose sum is σ = 111495787200. Its totient is φ = 52503278720.

The previous prime is 81177317399. The next prime is 81177317509. The reversal of 81177317493 is 39471377118.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81177317493 - 2⁸ = 81177317237 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81177317393) 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, 1821498 + ... + 1865531.

It is an arithmetic number, because the mean of its divisors is an integer number (6968486700).

Almost surely, 2^81177317493 is an apocalyptic number.

It is an amenable number.

81177317493 is a deficient number, since it is larger than the sum of its proper divisors (30318469707).

81177317493 is a wasteful number, since it uses less digits than its factorization.

81177317493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3687252.

The product of its digits is 889056, while the sum is 51.

The spelling of 81177317493 in words is "eighty-one billion, one hundred seventy-seven million, three hundred seventeen thousand, four hundred ninety-three".