81158725 has 12 divisors (see below), whose sum is σ = 101308000. Its totient is φ = 64494000.

The previous prime is 81158719. The next prime is 81158729. The reversal of 81158725 is 52785118.

It is not a de Polignac number, because 81158725 - 2²¹ = 79061573 is a prime.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81158729) 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, 6975 + ... + 14524.

Almost surely, 2^81158725 is an apocalyptic number.

It is an amenable number.

81158725 is a deficient number, since it is larger than the sum of its proper divisors (20149275).

81158725 is a wasteful number, since it uses less digits than its factorization.

81158725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21660 (or 21655 counting only the distinct ones).

The product of its digits is 22400, while the sum is 37.

The square root of 81158725 is about 9008.8137398883. The cubic root of 81158725 is about 432.9573052858.

It can be divided in two parts, 811 and 58725, that added together give a square (59536 = 244²).

The spelling of 81158725 in words is "eighty-one million, one hundred fifty-eight thousand, seven hundred twenty-five".