85981681 has 4 divisors (see below), whose sum is σ = 86001664. Its totient is φ = 85961700.

The previous prime is 85981661. The next prime is 85981691. The reversal of 85981681 is 18618958.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18618958 = 2 ⋅9309479.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-85981681 is a prime.

It is a super-2 number, since 2×85981681² = 14785698935171522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85981601) 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, 585 + ... + 13126.

It is an arithmetic number, because the mean of its divisors is an integer number (21500416).

Almost surely, 2^85981681 is an apocalyptic number.

It is an amenable number.

85981681 is a deficient number, since it is larger than the sum of its proper divisors (19983).

85981681 is a wasteful number, since it uses less digits than its factorization.

85981681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19982.

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

The square root of 85981681 is about 9272.6307486064. The cubic root of 85981681 is about 441.3691528725.

The spelling of 85981681 in words is "eighty-five million, nine hundred eighty-one thousand, six hundred eighty-one".