81768913 has 8 divisors (see below), whose sum is σ = 86234720. Its totient is φ = 77319360.

The previous prime is 81768847. The next prime is 81768923. The reversal of 81768913 is 31986718.

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

It is a de Polignac number, because none of the positive numbers 2^k-81768913 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81768913.

It is not an unprimeable number, because it can be changed into a prime (81768923) 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, 7081 + ... + 14617.

It is an arithmetic number, because the mean of its divisors is an integer number (10779340).

Almost surely, 2^81768913 is an apocalyptic number.

It is an amenable number.

81768913 is a deficient number, since it is larger than the sum of its proper divisors (4465807).

81768913 is a wasteful number, since it uses less digits than its factorization.

81768913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8127.

The product of its digits is 72576, while the sum is 43.

The square root of 81768913 is about 9042.6164908172. The cubic root of 81768913 is about 434.0396535508.

The spelling of 81768913 in words is "eighty-one million, seven hundred sixty-eight thousand, nine hundred thirteen".