643877569 has 2 divisors, whose sum is σ = 643877570. Its totient is φ = 643877568.

The previous prime is 643877551. The next prime is 643877579. The reversal of 643877569 is 965778346.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 581388544 + 62489025 = 24112^2 + 7905^2 .

It is a cyclic number.

It is not a de Polignac number, because 643877569 - 2²¹ = 641780417 is a prime.

It is a super-2 number, since 2×643877569² = 829156647722699522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (643877539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321938784 + 321938785.

It is an arithmetic number, because the mean of its divisors is an integer number (321938785).

Almost surely, 2^643877569 is an apocalyptic number.

It is an amenable number.

643877569 is a deficient number, since it is larger than the sum of its proper divisors (1).

643877569 is an equidigital number, since it uses as much as digits as its factorization.

643877569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7620480, while the sum is 55.

The square root of 643877569 is about 25374.7427376121. The cubic root of 643877569 is about 863.5107831637.

It can be divided in two parts, 643877 and 569, that added together give a palindrome (644446).

The spelling of 643877569 in words is "six hundred forty-three million, eight hundred seventy-seven thousand, five hundred sixty-nine".