7728605721369 has 45 divisors (see below), whose sum is σ = 12502134496269. Its totient is φ = 4755864896640.

The previous prime is 7728605721311. The next prime is 7728605721373. The reversal of 7728605721369 is 9631275068277.

The square root of 7728605721369 is 2780037.

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

7728605721369 is a `hidden beast` number, since 7 + 7 + 2 + 8 + 605 + 7 + 2 + 13 + 6 + 9 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 834893375625 + 6893712345744 = 913725^2 + 2625588^2 .

It is not a de Polignac number, because 7728605721369 - 2²³ = 7728597332761 is a prime.

It is a super-2 number, since 2×7728605721369² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (7728605721769) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 325252449 + ... + 325276209.

Almost surely, 2^{7728605721369} is an apocalyptic number.

7728605721369 is the 2780037-th square number.

7728605721369 is the 1390019-th centered octagonal number.

It is an amenable number.

7728605721369 is a deficient number, since it is larger than the sum of its proper divisors (4773528774900).

7728605721369 is an frugal number, since it uses more digits than its factorization.

7728605721369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47560 (or 23777 counting only the distinct ones).

The product of its (nonzero) digits is 53343360, while the sum is 63.

The spelling of 7728605721369 in words is "seven trillion, seven hundred twenty-eight billion, six hundred five million, seven hundred twenty-one thousand, three hundred sixty-nine".