6645965412529 has 27 divisors (see below), whose sum is σ = 7055920797579. Its totient is φ = 6258915679680.

The previous prime is 6645965412517. The next prime is 6645965412533. The reversal of 6645965412529 is 9252145695466.

It is a happy number.

The square root of 6645965412529 is 2577977.

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., 4998233762929 + 1647731649600 = 2235673^2 + 1283640^2 .

It is not a de Polignac number, because 6645965412529 - 2¹⁵ = 6645965379761 is a prime.

It is a super-2 number, since 2×6645965412529² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6645965422529) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 11804556402 + ... + 11804556964.

Almost surely, 2^{6645965412529} is an apocalyptic number.

6645965412529 is the 2577977-th square number.

6645965412529 is the 1288989-th centered octagonal number.

It is an amenable number.

6645965412529 is a deficient number, since it is larger than the sum of its proper divisors (409955385050).

6645965412529 is an frugal number, since it uses more digits than its factorization.

6645965412529 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1646 (or 823 counting only the distinct ones).

The product of its digits is 139968000, while the sum is 64.

Multiplying 6645965412529 by its sum of digits (64), we get a square (425341786401856 = 20623816²).

The spelling of 6645965412529 in words is "six trillion, six hundred forty-five billion, nine hundred sixty-five million, four hundred twelve thousand, five hundred twenty-nine".