81597225 has 12 divisors (see below), whose sum is σ = 134907536. Its totient is φ = 43518480.

The previous prime is 81597221. The next prime is 81597233. The reversal of 81597225 is 52279518.

It is not a de Polignac number, because 81597225 - 2² = 81597221 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81597221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 543907 + ... + 544056.

Almost surely, 2^81597225 is an apocalyptic number.

It is an amenable number.

81597225 is a deficient number, since it is larger than the sum of its proper divisors (53310311).

81597225 is a wasteful number, since it uses less digits than its factorization.

81597225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1087976 (or 1087971 counting only the distinct ones).

The product of its digits is 50400, while the sum is 39.

The square root of 81597225 is about 9033.1182323714. The cubic root of 81597225 is about 433.7356602047.

The spelling of 81597225 in words is "eighty-one million, five hundred ninety-seven thousand, two hundred twenty-five".