643399643 has 2 divisors, whose sum is σ = 643399644. Its totient is φ = 643399642.

The previous prime is 643399633. The next prime is 643399693. The reversal of 643399643 is 346993346.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643399643 - 2¹² = 643395547 is a prime.

It is a super-2 number, since 2×643399643² = 827926201225054898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (643399613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321699821 + 321699822.

It is an arithmetic number, because the mean of its divisors is an integer number (321699822).

Almost surely, 2^643399643 is an apocalyptic number.

643399643 is a deficient number, since it is larger than the sum of its proper divisors (1).

643399643 is an equidigital number, since it uses as much as digits as its factorization.

643399643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1259712, while the sum is 47.

The square root of 643399643 is about 25365.3236328654. The cubic root of 643399643 is about 863.2970798006.

The spelling of 643399643 in words is "six hundred forty-three million, three hundred ninety-nine thousand, six hundred forty-three".