81231725 has 12 divisors (see below), whose sum is σ = 101672064. Its totient is φ = 64375920.

The previous prime is 81231679. The next prime is 81231737. The reversal of 81231725 is 52713218.

It is not a de Polignac number, because 81231725 - 2²⁰ = 80183149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12509 + ... + 17858.

It is an arithmetic number, because the mean of its divisors is an integer number (8472672).

Almost surely, 2^81231725 is an apocalyptic number.

It is an amenable number.

81231725 is a deficient number, since it is larger than the sum of its proper divisors (20440339).

81231725 is a wasteful number, since it uses less digits than its factorization.

81231725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30484 (or 30479 counting only the distinct ones).

The product of its digits is 3360, while the sum is 29.

The square root of 81231725 is about 9012.8644170430. The cubic root of 81231725 is about 433.0870773747.

The spelling of 81231725 in words is "eighty-one million, two hundred thirty-one thousand, seven hundred twenty-five".