72685777609 has 9 divisors (see below), whose sum is σ = 77217788487. Its totient is φ = 68405829984.

The previous prime is 72685777607. The next prime is 72685777613. The reversal of 72685777609 is 90677758627.

The square root of 72685777609 is 269603.

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., 56589273225 + 16096504384 = 237885^2 + 126872^2 .

It is not a de Polignac number, because 72685777609 - 2¹ = 72685777607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72685777601) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4575322 + ... + 4591180.

Almost surely, 2^72685777609 is an apocalyptic number.

72685777609 is the 269603-rd square number.

72685777609 is the 134802-nd centered octagonal number.

It is an amenable number.

72685777609 is a deficient number, since it is larger than the sum of its proper divisors (4532010878).

72685777609 is an frugal number, since it uses more digits than its factorization.

72685777609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31752 (or 15876 counting only the distinct ones).

The product of its (nonzero) digits is 62233920, while the sum is 64.

Multiplying 72685777609 by its sum of digits (64), we get a square (4651889766976 = 2156824²).

The spelling of 72685777609 in words is "seventy-two billion, six hundred eighty-five million, seven hundred seventy-seven thousand, six hundred nine".