81684992100625 has 45 divisors (see below), whose sum is σ = 103164399714519. Its totient is φ = 64656950112000.

The previous prime is 81684992100563. The next prime is 81684992100643. The reversal of 81684992100625 is 52600129948618.

The square root of 81684992100625 is 9037975.

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 66195163153681 + 15489828946944 = 8136041^2 + 3935712^2 .

It is not a de Polignac number, because 81684992100625 - 2⁷ = 81684992100497 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 44 ways as a sum of consecutive naturals, for example, 21917087512 + ... + 21917091238.

Almost surely, 2^{81684992100625} is an apocalyptic number.

81684992100625 is the 9037975-th square number.

81684992100625 is the 4518988-th centered octagonal number.

It is an amenable number.

81684992100625 is a deficient number, since it is larger than the sum of its proper divisors (21479407613894).

81684992100625 is an frugal number, since it uses more digits than its factorization.

81684992100625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7668 (or 3829 counting only the distinct ones).

The product of its (nonzero) digits is 14929920, while the sum is 61.

The spelling of 81684992100625 in words is "eighty-one trillion, six hundred eighty-four billion, nine hundred ninety-two million, one hundred thousand, six hundred twenty-five".