85891681 has 4 divisors (see below), whose sum is σ = 85911700. Its totient is φ = 85871664.

The previous prime is 85891661. The next prime is 85891693. The reversal of 85891681 is 18619858.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18619858 = 2 ⋅9309929.

It can be written as a sum of positive squares in 2 ways, for example, as 67914081 + 17977600 = 8241^2 + 4240^2 .

It is a cyclic number.

It is not a de Polignac number, because 85891681 - 2¹⁹ = 85367393 is a prime.

It is a super-2 number, since 2×85891681² = 14754761730011522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85891661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 666 + ... + 13123.

It is an arithmetic number, because the mean of its divisors is an integer number (21477925).

Almost surely, 2^85891681 is an apocalyptic number.

It is an amenable number.

85891681 is a deficient number, since it is larger than the sum of its proper divisors (20019).

85891681 is a wasteful number, since it uses less digits than its factorization.

85891681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20018.

The product of its digits is 138240, while the sum is 46.

The square root of 85891681 is about 9267.7764862992. The cubic root of 85891681 is about 441.2151003222.

The spelling of 85891681 in words is "eighty-five million, eight hundred ninety-one thousand, six hundred eighty-one".