81535917 has 8 divisors (see below), whose sum is σ = 108784224. Its totient is φ = 54322448.

The previous prime is 81535879. The next prime is 81535931. The reversal of 81535917 is 71953518.

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 81535917 - 2²² = 77341613 is a prime.

It is a super-2 number, since 2×81535917² = 13296211522061778, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81535957) 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, 2643 + ... + 13040.

It is an arithmetic number, because the mean of its divisors is an integer number (13598028).

Almost surely, 2^81535917 is an apocalyptic number.

It is an amenable number.

81535917 is a deficient number, since it is larger than the sum of its proper divisors (27248307).

81535917 is a wasteful number, since it uses less digits than its factorization.

81535917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17419.

The product of its digits is 37800, while the sum is 39.

The square root of 81535917 is about 9029.7240821633. The cubic root of 81535917 is about 433.6270040240.

The spelling of 81535917 in words is "eighty-one million, five hundred thirty-five thousand, nine hundred seventeen".