85666591 has 4 divisors (see below), whose sum is σ = 85699800. Its totient is φ = 85633384.

The previous prime is 85666561. The next prime is 85666597. The reversal of 85666591 is 19566658.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19566658 = 2 ⋅9783329.

It is a cyclic number.

It is not a de Polignac number, because 85666591 - 2⁷ = 85666463 is a prime.

It is a super-2 number, since 2×85666591² = 14677529627122562, 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 (85666597) 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, 12376 + ... + 18013.

It is an arithmetic number, because the mean of its divisors is an integer number (21424950).

Almost surely, 2^85666591 is an apocalyptic number.

85666591 is a deficient number, since it is larger than the sum of its proper divisors (33209).

85666591 is a wasteful number, since it uses less digits than its factorization.

85666591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33208.

The product of its digits is 388800, while the sum is 46.

The square root of 85666591 is about 9255.6248303397. The cubic root of 85666591 is about 440.8293431822.

The spelling of 85666591 in words is "eighty-five million, six hundred sixty-six thousand, five hundred ninety-one".