81513336425 has 12 divisors (see below), whose sum is σ = 101634976716. Its totient is φ = 64850385600.

The previous prime is 81513336413. The next prime is 81513336427. The reversal of 81513336425 is 52463331518.

It can be written as a sum of positive squares in 6 ways, for example, as 5195958889 + 76317377536 = 72083^2 + 276256^2 .

It is not a de Polignac number, because 81513336425 - 2⁶ = 81513336361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81513336427) 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, 9002474 + ... + 9011523.

It is an arithmetic number, because the mean of its divisors is an integer number (8469581393).

Almost surely, 2^81513336425 is an apocalyptic number.

It is an amenable number.

81513336425 is a deficient number, since it is larger than the sum of its proper divisors (20121640291).

81513336425 is a wasteful number, since it uses less digits than its factorization.

81513336425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18014188 (or 18014183 counting only the distinct ones).

The product of its digits is 259200, while the sum is 41.

The spelling of 81513336425 in words is "eighty-one billion, five hundred thirteen million, three hundred thirty-six thousand, four hundred twenty-five".