81517859 has 8 divisors (see below), whose sum is σ = 83569680. Its totient is φ = 79491456.

The previous prime is 81517841. The next prime is 81517901. The reversal of 81517859 is 95871518.

It is a happy number.

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 81517859 - 2²⁰ = 80469283 is a prime.

It is a super-2 number, since 2×81517859² = 13290322671887762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81517459) 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, 224 + ... + 12770.

It is an arithmetic number, because the mean of its divisors is an integer number (10446210).

Almost surely, 2^81517859 is an apocalyptic number.

81517859 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

81517859 is a deficient number, since it is larger than the sum of its proper divisors (2051821).

81517859 is a wasteful number, since it uses less digits than its factorization.

81517859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12709.

The product of its digits is 100800, while the sum is 44.

The square root of 81517859 is about 9028.7241069821. The cubic root of 81517859 is about 433.5949894433.

The spelling of 81517859 in words is "eighty-one million, five hundred seventeen thousand, eight hundred fifty-nine".