72511602781 has 4 divisors (see below), whose sum is σ = 72517445532. Its totient is φ = 72505760032.

The previous prime is 72511602767. The next prime is 72511602799. The reversal of 72511602781 is 18720611527.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40509612900 + 32001989881 = 201270^2 + 178891^2 .

It is a cyclic number.

It is not a de Polignac number, because 72511602781 - 2²⁷ = 72377385053 is a prime.

It is a super-2 number, since 2×72511602781² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72511602181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2902720 + ... + 2927593.

It is an arithmetic number, because the mean of its divisors is an integer number (18129361383).

Almost surely, 2^72511602781 is an apocalyptic number.

It is an amenable number.

72511602781 is a deficient number, since it is larger than the sum of its proper divisors (5842751).

72511602781 is a wasteful number, since it uses less digits than its factorization.

72511602781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5842750.

The product of its (nonzero) digits is 47040, while the sum is 40.

The spelling of 72511602781 in words is "seventy-two billion, five hundred eleven million, six hundred two thousand, seven hundred eighty-one".