81457999491 has 8 divisors (see below), whose sum is σ = 118484362944. Its totient is φ = 49368484520.

The previous prime is 81457999463. The next prime is 81457999529. The reversal of 81457999491 is 19499975418.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81457999491 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81457999591) 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, 1234212081 + ... + 1234212146.

It is an arithmetic number, because the mean of its divisors is an integer number (14810545368).

Almost surely, 2^81457999491 is an apocalyptic number.

81457999491 is a deficient number, since it is larger than the sum of its proper divisors (37026363453).

81457999491 is a wasteful number, since it uses less digits than its factorization.

81457999491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2468424241.

The product of its digits is 29393280, while the sum is 66.

The spelling of 81457999491 in words is "eighty-one billion, four hundred fifty-seven million, nine hundred ninety-nine thousand, four hundred ninety-one".