72781613 has 4 divisors (see below), whose sum is σ = 72965340. Its totient is φ = 72597888.

The previous prime is 72781567. The next prime is 72781649. The reversal of 72781613 is 31618727.

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 60264169 + 12517444 = 7763^2 + 3538^2 .

It is a cyclic number.

It is not a de Polignac number, because 72781613 - 2⁶ = 72781549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72781693) 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, 91268 + ... + 92061.

It is an arithmetic number, because the mean of its divisors is an integer number (18241335).

Almost surely, 2^72781613 is an apocalyptic number.

It is an amenable number.

72781613 is a deficient number, since it is larger than the sum of its proper divisors (183727).

72781613 is a wasteful number, since it uses less digits than its factorization.

72781613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183726.

The product of its digits is 14112, while the sum is 35.

The square root of 72781613 is about 8531.2140402173. The cubic root of 72781613 is about 417.5167392622.

The spelling of 72781613 in words is "seventy-two million, seven hundred eighty-one thousand, six hundred thirteen".