3939681128769 has 9 divisors (see below), whose sum is σ = 5690659120419. Its totient is φ = 2626450116120.

The previous prime is 3939681128693. The next prime is 3939681128777. The reversal of 3939681128769 is 9678211869393.

The square root of 3939681128769 is 1984863.

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

3939681128769 is a `hidden beast` number, since 39 + 396 + 81 + 128 + 7 + 6 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 302650718769 + 3637030410000 = 550137^2 + 1907100^2 .

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

It is not a de Polignac number, because 3939681128769 - 2¹¹ = 3939681126721 is a prime.

It is a super-2 number, since 2×3939681128769² (a number of 26 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 3939681128697 and 3939681128706.

It is not an unprimeable number, because it can be changed into a prime (3939681128569) 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, 5623779 + ... + 6285399.

Almost surely, 2^{3939681128769} is an apocalyptic number.

3939681128769 is the 1984863-rd square number.

3939681128769 is the 992432-nd centered octagonal number.

It is an amenable number.

3939681128769 is a deficient number, since it is larger than the sum of its proper divisors (1750977991650).

3939681128769 is an frugal number, since it uses more digits than its factorization.

3939681128769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1323248 (or 661624 counting only the distinct ones).

The product of its digits is 211631616, while the sum is 72.

The spelling of 3939681128769 in words is "three trillion, nine hundred thirty-nine billion, six hundred eighty-one million, one hundred twenty-eight thousand, seven hundred sixty-nine".