72500409081 has 9 divisors (see below), whose sum is σ = 104723979919. Its totient is φ = 48333067536.

The previous prime is 72500409049. The next prime is 72500409083. The reversal of 72500409081 is 18090400527.

The square root of 72500409081 is 269259.

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

72500409081 is a `hidden beast` number, since 72 + 500 + 4 + 0 + 9 + 0 + 81 = 666.

It can be written as a sum of positive squares in only one way, i.e., 58721405625 + 13779003456 = 242325^2 + 117384^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 72500409081 - 2⁵ = 72500409049 is a prime.

It is a super-2 number, since 2×72500409081² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (72500409083) by changing a digit.

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 8 ways as a sum of consecutive naturals, for example, 762901 + ... + 852653.

Almost surely, 2^72500409081 is an apocalyptic number.

72500409081 is the 269259-th square number.

72500409081 is the 134630-th centered octagonal number.

It is an amenable number.

72500409081 is a deficient number, since it is larger than the sum of its proper divisors (32223570838).

72500409081 is an frugal number, since it uses more digits than its factorization.

72500409081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179512 (or 89756 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

Multiplying 72500409081 by its sum of digits (36), we get a square (2610014726916 = 1615554²).

The spelling of 72500409081 in words is "seventy-two billion, five hundred million, four hundred nine thousand, eighty-one".