643799983 has 2 divisors, whose sum is σ = 643799984. Its totient is φ = 643799982.

The previous prime is 643799941. The next prime is 643799987. The reversal of 643799983 is 389997346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643799983 - 2¹⁷ = 643668911 is a prime.

It is a super-2 number, since 2×643799983² = 828956836221600578, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643799987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321899991 + 321899992.

It is an arithmetic number, because the mean of its divisors is an integer number (321899992).

Almost surely, 2^643799983 is an apocalyptic number.

643799983 is a deficient number, since it is larger than the sum of its proper divisors (1).

643799983 is an equidigital number, since it uses as much as digits as its factorization.

643799983 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8817984, while the sum is 58.

The square root of 643799983 is about 25373.2138878779. The cubic root of 643799983 is about 863.4760979782.

The spelling of 643799983 in words is "six hundred forty-three million, seven hundred ninety-nine thousand, nine hundred eighty-three".