81560725 has 6 divisors (see below), whose sum is σ = 101135330. Its totient is φ = 65248560.

The previous prime is 81560719. The next prime is 81560729. The reversal of 81560725 is 52706518.

It can be written as a sum of positive squares in 3 ways, for example, as 1764 + 81558961 = 42^2 + 9031^2 .

It is not a de Polignac number, because 81560725 - 2¹⁹ = 81036437 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81560729) 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, 1631190 + ... + 1631239.

Almost surely, 2^81560725 is an apocalyptic number.

It is an amenable number.

81560725 is a deficient number, since it is larger than the sum of its proper divisors (19574605).

81560725 is a wasteful number, since it uses less digits than its factorization.

81560725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3262439 (or 3262434 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 81560725 is about 9031.0976630751. The cubic root of 81560725 is about 433.6709778059.

The spelling of 81560725 in words is "eighty-one million, five hundred sixty thousand, seven hundred twenty-five".