85491981 has 12 divisors (see below), whose sum is σ = 123583200. Its totient is φ = 56950920.

The previous prime is 85491961. The next prime is 85492009. The reversal of 85491981 is 18919458.

85491981 is a `hidden beast` number, since 85 + 491 + 9 + 81 = 666.

It is not a de Polignac number, because 85491981 - 2⁵ = 85491949 is a prime.

It is a super-2 number, since 2×85491981² = 14617757630608722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85491961) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12496 + ... + 18086.

It is an arithmetic number, because the mean of its divisors is an integer number (10298600).

Almost surely, 2^85491981 is an apocalyptic number.

It is an amenable number.

85491981 is a deficient number, since it is larger than the sum of its proper divisors (38091219).

85491981 is a wasteful number, since it uses less digits than its factorization.

85491981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7296 (or 7293 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 85491981 is about 9246.1873764271. The cubic root of 85491981 is about 440.5296325369.

The spelling of 85491981 in words is "eighty-five million, four hundred ninety-one thousand, nine hundred eighty-one".