643253957 has 2 divisors, whose sum is σ = 643253958. Its totient is φ = 643253956.

The previous prime is 643253953. The next prime is 643253977. The reversal of 643253957 is 759352346.

643253957 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 641811556 + 1442401 = 25334^2 + 1201^2 .

It is a cyclic number.

It is not a de Polignac number, because 643253957 - 2² = 643253953 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643253953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321626978 + 321626979.

It is an arithmetic number, because the mean of its divisors is an integer number (321626979).

Almost surely, 2^643253957 is an apocalyptic number.

It is an amenable number.

643253957 is a deficient number, since it is larger than the sum of its proper divisors (1).

643253957 is an equidigital number, since it uses as much as digits as its factorization.

643253957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 680400, while the sum is 44.

The square root of 643253957 is about 25362.4517150846. The cubic root of 643253957 is about 863.2319156403.

The spelling of 643253957 in words is "six hundred forty-three million, two hundred fifty-three thousand, nine hundred fifty-seven".