641820492769 has 3 divisors (see below), whose sum is σ = 641821293907. Its totient is φ = 641819691632.

The previous prime is 641820492739. The next prime is 641820492787. The reversal of 641820492769 is 967294028146.

The square root of 641820492769 is 801137.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 607628045025 + 34192447744 = 779505^2 + 184912^2 .

It is not a de Polignac number, because 641820492769 - 2¹⁷ = 641820361697 is a prime.

It is a super-2 number, since 2×641820492769² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641820492739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 400569 + ... + 1201705.

Almost surely, 2^641820492769 is an apocalyptic number.

641820492769 is the 801137-th square number.

641820492769 is the 400569-th centered octagonal number.

It is an amenable number.

641820492769 is a deficient number, since it is larger than the sum of its proper divisors (801138).

641820492769 is an frugal number, since it uses more digits than its factorization.

641820492769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1602274 (or 801137 counting only the distinct ones).

The product of its (nonzero) digits is 10450944, while the sum is 58.

The spelling of 641820492769 in words is "six hundred forty-one billion, eight hundred twenty million, four hundred ninety-two thousand, seven hundred sixty-nine".