643352789 has 2 divisors, whose sum is σ = 643352790. Its totient is φ = 643352788.

The previous prime is 643352767. The next prime is 643352807. The reversal of 643352789 is 987253346.

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., 555780625 + 87572164 = 23575^2 + 9358^2 .

It is a cyclic number.

It is not a de Polignac number, because 643352789 - 2²⁰ = 642304213 is a prime.

It is a super-2 number, since 2×643352789² = 827805622228157042, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643352719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321676394 + 321676395.

It is an arithmetic number, because the mean of its divisors is an integer number (321676395).

Almost surely, 2^643352789 is an apocalyptic number.

It is an amenable number.

643352789 is a deficient number, since it is larger than the sum of its proper divisors (1).

643352789 is an equidigital number, since it uses as much as digits as its factorization.

643352789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1088640, while the sum is 47.

The square root of 643352789 is about 25364.4000323288. The cubic root of 643352789 is about 863.2761234615.

The spelling of 643352789 in words is "six hundred forty-three million, three hundred fifty-two thousand, seven hundred eighty-nine".