81712817 has 4 divisors (see below), whose sum is σ = 83097840. Its totient is φ = 80327796.

The previous prime is 81712801. The next prime is 81712819. The reversal of 81712817 is 71821718.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81712817 - 2⁴ = 81712801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81712819) 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, 692423 + ... + 692540.

It is an arithmetic number, because the mean of its divisors is an integer number (20774460).

Almost surely, 2^81712817 is an apocalyptic number.

It is an amenable number.

81712817 is a deficient number, since it is larger than the sum of its proper divisors (1385023).

81712817 is a wasteful number, since it uses less digits than its factorization.

81712817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1385022.

The product of its digits is 6272, while the sum is 35.

The square root of 81712817 is about 9039.5142015487. The cubic root of 81712817 is about 433.9403759752.

The spelling of 81712817 in words is "eighty-one million, seven hundred twelve thousand, eight hundred seventeen".