81285872 has 20 divisors (see below), whose sum is σ = 158888640. Its totient is φ = 40282368.

The previous prime is 81285863. The next prime is 81285877. The reversal of 81285872 is 27858218.

81285872 is nontrivially palindromic in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81285877) 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, 20672 + ... + 24287.

It is an arithmetic number, because the mean of its divisors is an integer number (7944432).

Almost surely, 2^81285872 is an apocalyptic number.

It is an amenable number.

81285872 is a deficient number, since it is larger than the sum of its proper divisors (77602768).

81285872 is a wasteful number, since it uses less digits than its factorization.

81285872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45080 (or 45074 counting only the distinct ones).

The product of its digits is 71680, while the sum is 41.

The square root of 81285872 is about 9015.8677896251. The cubic root of 81285872 is about 433.1832842751.

The spelling of 81285872 in words is "eighty-one million, two hundred eighty-five thousand, eight hundred seventy-two".