81580825 has 6 divisors (see below), whose sum is σ = 101160254. Its totient is φ = 65264640.

The previous prime is 81580823. The next prime is 81580843. The reversal of 81580825 is 52808518.

It can be written as a sum of positive squares in 3 ways, for example, as 1245456 + 80335369 = 1116^2 + 8963^2 .

It is not a de Polignac number, because 81580825 - 2¹ = 81580823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81580823) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1631592 + ... + 1631641.

Almost surely, 2^81580825 is an apocalyptic number.

It is an amenable number.

81580825 is a deficient number, since it is larger than the sum of its proper divisors (19579429).

81580825 is a wasteful number, since it uses less digits than its factorization.

81580825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3263243 (or 3263238 counting only the distinct ones).

The product of its (nonzero) digits is 25600, while the sum is 37.

The square root of 81580825 is about 9032.2104160610. The cubic root of 81580825 is about 433.7065998151.

The spelling of 81580825 in words is "eighty-one million, five hundred eighty thousand, eight hundred twenty-five".