81756317 has 4 divisors (see below), whose sum is σ = 81894780. Its totient is φ = 81617856.

The previous prime is 81756313. The next prime is 81756319. The reversal of 81756317 is 71365718.

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

It can be written as a sum of positive squares in 2 ways, for example, as 21631801 + 60124516 = 4651^2 + 7754^2 .

It is a cyclic number.

It is not a de Polignac number, because 81756317 - 2² = 81756313 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 (81756313) 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, 68342 + ... + 69527.

It is an arithmetic number, because the mean of its divisors is an integer number (20473695).

Almost surely, 2^81756317 is an apocalyptic number.

It is an amenable number.

81756317 is a deficient number, since it is larger than the sum of its proper divisors (138463).

81756317 is a wasteful number, since it uses less digits than its factorization.

81756317 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138462.

The product of its digits is 35280, while the sum is 38.

The square root of 81756317 is about 9041.9199841627. The cubic root of 81756317 is about 434.0173653567.

The spelling of 81756317 in words is "eighty-one million, seven hundred fifty-six thousand, three hundred seventeen".