643354639 has 2 divisors, whose sum is σ = 643354640. Its totient is φ = 643354638.

The previous prime is 643354637. The next prime is 643354711. The reversal of 643354639 is 936453346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643354639 - 2¹ = 643354637 is a prime.

Together with 643354637, it forms a pair of twin primes.

It is equal to p_33465895 and since 643354639 and 33465895 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 643354595 and 643354604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643354633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321677319 + 321677320.

It is an arithmetic number, because the mean of its divisors is an integer number (321677320).

Almost surely, 2^643354639 is an apocalyptic number.

643354639 is a deficient number, since it is larger than the sum of its proper divisors (1).

643354639 is an equidigital number, since it uses as much as digits as its factorization.

643354639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 699840, while the sum is 43.

The square root of 643354639 is about 25364.4365007386. The cubic root of 643354639 is about 863.2769509283.

The spelling of 643354639 in words is "six hundred forty-three million, three hundred fifty-four thousand, six hundred thirty-nine".