81850917 has 16 divisors (see below), whose sum is σ = 115197120. Its totient is φ = 51552000.

The previous prime is 81850913. The next prime is 81850927. The reversal of 81850917 is 71905818.

It is not a de Polignac number, because 81850917 - 2² = 81850913 is a prime.

It is a super-2 number, since 2×81850917² = 13399145227481778, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81850913) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21067 + ... + 24647.

It is an arithmetic number, because the mean of its divisors is an integer number (7199820).

Almost surely, 2^81850917 is an apocalyptic number.

It is an amenable number.

81850917 is a deficient number, since it is larger than the sum of its proper divisors (33346203).

81850917 is a wasteful number, since it uses less digits than its factorization.

81850917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4004.

The product of its (nonzero) digits is 20160, while the sum is 39.

The square root of 81850917 is about 9047.1496616338. The cubic root of 81850917 is about 434.1847009151.

The spelling of 81850917 in words is "eighty-one million, eight hundred fifty thousand, nine hundred seventeen".