643793993 has 2 divisors, whose sum is σ = 643793994. Its totient is φ = 643793992.

The previous prime is 643793977. The next prime is 643794001. The reversal of 643793993 is 399397346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 639685264 + 4108729 = 25292^2 + 2027^2 .

It is a cyclic number.

It is not a de Polignac number, because 643793993 - 2⁴ = 643793977 is a prime.

It is not a weakly prime, because it can be changed into another prime (643792993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321896996 + 321896997.

It is an arithmetic number, because the mean of its divisors is an integer number (321896997).

Almost surely, 2^643793993 is an apocalyptic number.

It is an amenable number.

643793993 is a deficient number, since it is larger than the sum of its proper divisors (1).

643793993 is an equidigital number, since it uses as much as digits as its factorization.

643793993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3306744, while the sum is 53.

The square root of 643793993 is about 25373.0958497382. The cubic root of 643793993 is about 863.4734200047.

The spelling of 643793993 in words is "six hundred forty-three million, seven hundred ninety-three thousand, nine hundred ninety-three".