81517379 has 4 divisors (see below), whose sum is σ = 83413176. Its totient is φ = 79621584.

The previous prime is 81517369. The next prime is 81517417. The reversal of 81517379 is 97371518.

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-81517379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81517309) 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, 947834 + ... + 947919.

It is an arithmetic number, because the mean of its divisors is an integer number (20853294).

Almost surely, 2^81517379 is an apocalyptic number.

81517379 is a deficient number, since it is larger than the sum of its proper divisors (1895797).

81517379 is a wasteful number, since it uses less digits than its factorization.

81517379 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1895796.

The product of its digits is 52920, while the sum is 41.

The square root of 81517379 is about 9028.6975251140. The cubic root of 81517379 is about 433.5941383987.

The spelling of 81517379 in words is "eighty-one million, five hundred seventeen thousand, three hundred seventy-nine".