81388679 has 4 divisors (see below), whose sum is σ = 81810576. Its totient is φ = 80966784.

The previous prime is 81388669. The next prime is 81388687. The reversal of 81388679 is 97688318.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81388679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81388669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 210659 + ... + 211044.

It is an arithmetic number, because the mean of its divisors is an integer number (20452644).

Almost surely, 2^81388679 is an apocalyptic number.

81388679 is a deficient number, since it is larger than the sum of its proper divisors (421897).

81388679 is a wasteful number, since it uses less digits than its factorization.

81388679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 421896.

The product of its digits is 580608, while the sum is 50.

The square root of 81388679 is about 9021.5674358728. The cubic root of 81388679 is about 433.3658314220.

The spelling of 81388679 in words is "eighty-one million, three hundred eighty-eight thousand, six hundred seventy-nine".