81051812416 has 63 divisors (see below), whose sum is σ = 169838515161. Its totient is φ = 38372465664.

The previous prime is 81051812371. The next prime is 81051812419. The reversal of 81051812416 is 61421815018.

The square root of 81051812416 is 284696.

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

It can be written as a sum of positive squares in only one way, i.e., 2149249600 + 78902562816 = 46360^2 + 280896^2 .

It is not an unprimeable number, because it can be changed into a prime (81051812419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 43272856 + ... + 43274728.

It is an arithmetic number, because the mean of its divisors is an integer number (2695849447).

Almost surely, 2^81051812416 is an apocalyptic number.

81051812416 is the 284696-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81051812416

81051812416 is an abundant number, since it is smaller than the sum of its proper divisors (88786702745).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81051812416 is an frugal number, since it uses more digits than its factorization.

81051812416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3796 (or 1894 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 37.

The spelling of 81051812416 in words is "eighty-one billion, fifty-one million, eight hundred twelve thousand, four hundred sixteen".