81125280625 has 15 divisors (see below), whose sum is σ = 101383049383. Its totient is φ = 64894528000.

The previous prime is 81125280611. The next prime is 81125280641. The reversal of 81125280625 is 52608252118.

The square root of 81125280625 is 284825.

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

It can be written as a sum of positive squares in 7 ways, for example, as 42934740849 + 38190539776 = 207207^2 + 195424^2 .

It is not a de Polignac number, because 81125280625 - 2⁹ = 81125280113 is a prime.

It is a super-2 number, since 2×81125280625² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 7114929 + ... + 7126321.

Almost surely, 2^81125280625 is an apocalyptic number.

81125280625 is the 284825-th square number.

81125280625 is the 142413-rd centered octagonal number.

It is an amenable number.

81125280625 is a deficient number, since it is larger than the sum of its proper divisors (20257768758).

81125280625 is an frugal number, since it uses more digits than its factorization.

81125280625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22806 (or 11398 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 40.

The spelling of 81125280625 in words is "eighty-one billion, one hundred twenty-five million, two hundred eighty thousand, six hundred twenty-five".