81295125129 has 27 divisors (see below), whose sum is σ = 118726610197. Its totient is φ = 53603124000.

The previous prime is 81295125127. The next prime is 81295125161. The reversal of 81295125129 is 92152159218.

It is a happy number.

The square root of 81295125129 is 285123.

It is a perfect power (a square), and thus also a powerful number.

81295125129 is a `hidden beast` number, since 8 + 1 + 2 + 9 + 512 + 5 + 129 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 34327566729 + 46967558400 = 185277^2 + 216720^2 .

It is not a de Polignac number, because 81295125129 - 2¹ = 81295125127 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81295125127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 86391799 + ... + 86392739.

Almost surely, 2^81295125129 is an apocalyptic number.

81295125129 is the 285123-rd square number.

81295125129 is the 142562-nd centered octagonal number.

It is an amenable number.

81295125129 is a deficient number, since it is larger than the sum of its proper divisors (37431485068).

81295125129 is an frugal number, since it uses more digits than its factorization.

81295125129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2090 (or 1045 counting only the distinct ones).

The product of its digits is 129600, while the sum is 45.

The spelling of 81295125129 in words is "eighty-one billion, two hundred ninety-five million, one hundred twenty-five thousand, one hundred twenty-nine".