81461985 has 16 divisors (see below), whose sum is σ = 142188480. Its totient is φ = 39496640.

The previous prime is 81461983. The next prime is 81462001. The reversal of 81461985 is 58916418.

It is not a de Polignac number, because 81461985 - 2¹ = 81461983 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81461983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 246690 + ... + 247019.

It is an arithmetic number, because the mean of its divisors is an integer number (8886780).

Almost surely, 2^81461985 is an apocalyptic number.

It is an amenable number.

81461985 is a deficient number, since it is larger than the sum of its proper divisors (60726495).

81461985 is a wasteful number, since it uses less digits than its factorization.

81461985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 493728.

The product of its digits is 69120, while the sum is 42.

The square root of 81461985 is about 9025.6293409379. The cubic root of 81461985 is about 433.4959018569.

The spelling of 81461985 in words is "eighty-one million, four hundred sixty-one thousand, nine hundred eighty-five".