81457777691 has 8 divisors (see below), whose sum is σ = 81617515680. Its totient is φ = 81298099008.

The previous prime is 81457777679. The next prime is 81457777697. The reversal of 81457777691 is 19677775418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81457777691 - 2³⁴ = 64277908507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81457777697) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3560210 + ... + 3583016.

It is an arithmetic number, because the mean of its divisors is an integer number (10202189460).

Almost surely, 2^81457777691 is an apocalyptic number.

81457777691 is a deficient number, since it is larger than the sum of its proper divisors (159737989).

81457777691 is a wasteful number, since it uses less digits than its factorization.

81457777691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29653.

The product of its digits is 20744640, while the sum is 62.

The spelling of 81457777691 in words is "eighty-one billion, four hundred fifty-seven million, seven hundred seventy-seven thousand, six hundred ninety-one".