81717719 has 8 divisors (see below), whose sum is σ = 84714768. Its totient is φ = 78762240.

The previous prime is 81717707. The next prime is 81717721. The reversal of 81717719 is 91771718.

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

It is a cyclic number.

It is not a de Polignac number, because 81717719 - 2⁴ = 81717703 is a prime.

It is a super-2 number, since 2×81717719² = 13355571197125922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81717739) 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, 6362 + ... + 14279.

It is an arithmetic number, because the mean of its divisors is an integer number (10589346).

Almost surely, 2^81717719 is an apocalyptic number.

81717719 is a deficient number, since it is larger than the sum of its proper divisors (2997049).

81717719 is a wasteful number, since it uses less digits than its factorization.

81717719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20785.

The product of its digits is 24696, while the sum is 41.

The square root of 81717719 is about 9039.7853403718. The cubic root of 81717719 is about 433.9490532479.

The spelling of 81717719 in words is "eighty-one million, seven hundred seventeen thousand, seven hundred nineteen".