85177991 has 4 divisors (see below), whose sum is σ = 85217832. Its totient is φ = 85138152.

The previous prime is 85177979. The next prime is 85177997. The reversal of 85177991 is 19977158.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19977158 = 2 ⋅9988579.

It is a cyclic number.

It is not a de Polignac number, because 85177991 - 2¹⁴ = 85161607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85177997) 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, 16520 + ... + 21053.

It is an arithmetic number, because the mean of its divisors is an integer number (21304458).

Almost surely, 2^85177991 is an apocalyptic number.

85177991 is a deficient number, since it is larger than the sum of its proper divisors (39841).

85177991 is a wasteful number, since it uses less digits than its factorization.

85177991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39840.

The product of its digits is 158760, while the sum is 47.

The square root of 85177991 is about 9229.1923265257. The cubic root of 85177991 is about 439.9896536823.

It can be divided in two parts, 85177 and 991, that added together give a palindrome (86168).

The spelling of 85177991 in words is "eighty-five million, one hundred seventy-seven thousand, nine hundred ninety-one".