643934497 has 2 divisors, whose sum is σ = 643934498. Its totient is φ = 643934496.

The previous prime is 643934477. The next prime is 643934507. The reversal of 643934497 is 794439346.

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., 598829841 + 45104656 = 24471^2 + 6716^2 .

It is a cyclic number.

It is not a de Polignac number, because 643934497 - 2¹⁵ = 643901729 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643934497.

It is not a weakly prime, because it can be changed into another prime (643934477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321967248 + 321967249.

It is an arithmetic number, because the mean of its divisors is an integer number (321967249).

Almost surely, 2^643934497 is an apocalyptic number.

It is an amenable number.

643934497 is a deficient number, since it is larger than the sum of its proper divisors (1).

643934497 is an equidigital number, since it uses as much as digits as its factorization.

643934497 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1959552, while the sum is 49.

The square root of 643934497 is about 25375.8644581815. The cubic root of 643934497 is about 863.5362313211.

The spelling of 643934497 in words is "six hundred forty-three million, nine hundred thirty-four thousand, four hundred ninety-seven".