643570769 has 2 divisors, whose sum is σ = 643570770. Its totient is φ = 643570768.

The previous prime is 643570747. The next prime is 643570799. The reversal of 643570769 is 967075346.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 602457025 + 41113744 = 24545^2 + 6412^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643570769 is a prime.

It is a super-2 number, since 2×643570769² = 828366669422502722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (643570709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321785384 + 321785385.

It is an arithmetic number, because the mean of its divisors is an integer number (321785385).

Almost surely, 2^643570769 is an apocalyptic number.

It is an amenable number.

643570769 is a deficient number, since it is larger than the sum of its proper divisors (1).

643570769 is an equidigital number, since it uses as much as digits as its factorization.

643570769 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 952560, while the sum is 47.

The square root of 643570769 is about 25368.6966358148. The cubic root of 643570769 is about 863.3736105033.

The spelling of 643570769 in words is "six hundred forty-three million, five hundred seventy thousand, seven hundred sixty-nine".