81325665 has 12 divisors (see below), whose sum is σ = 140964564. Its totient is φ = 43373664.

The previous prime is 81325661. The next prime is 81325693. The reversal of 81325665 is 56652318.

It can be written as a sum of positive squares in 2 ways, for example, as 41370624 + 39955041 = 6432^2 + 6321^2 .

It is not a de Polignac number, because 81325665 - 2² = 81325661 is a prime.

It is a super-2 number, since 2×81325665² = 13227727575384450, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81325661) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 903574 + ... + 903663.

It is an arithmetic number, because the mean of its divisors is an integer number (11747047).

Almost surely, 2^81325665 is an apocalyptic number.

It is an amenable number.

81325665 is a deficient number, since it is larger than the sum of its proper divisors (59638899).

81325665 is a wasteful number, since it uses less digits than its factorization.

81325665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1807248 (or 1807245 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 81325665 is about 9018.0743509909. The cubic root of 81325665 is about 433.2539601499.

The spelling of 81325665 in words is "eighty-one million, three hundred twenty-five thousand, six hundred sixty-five".