81000072000016 has 135 divisors (see below), whose sum is σ = 180540521821173. Its totient is φ = 35182095636480.

The previous prime is 81000071999911. The next prime is 81000072000037. The reversal of 81000072000016 is 61000027000018.

The square root of 81000072000016 is 9000004.

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

It can be written as a sum of positive squares in 13 ways, for example, as 40269126873616 + 40730945126400 = 6345796^2 + 6382080^2 .

It is a super-2 number, since 2×81000072000016² (a number of 29 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 7955998446 + ... + 7956008626.

Almost surely, 2^{81000072000016} is an apocalyptic number.

81000072000016 is the 9000004-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81000072000016

81000072000016 is an abundant number, since it is smaller than the sum of its proper divisors (99540449821157).

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

81000072000016 is an equidigital number, since it uses as much as digits as its factorization.

81000072000016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20430 (or 10213 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 25.

The spelling of 81000072000016 in words is "eighty-one trillion, seventy-two million, sixteen", and thus it is an aban number and an uban number.