643962639 has 8 divisors (see below), whose sum is σ = 873169920. Its totient is φ = 422031896.

The previous prime is 643962637. The next prime is 643962643. The reversal of 643962639 is 936269346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643962639 - 2¹ = 643962637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643962637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1818927 + ... + 1819280.

It is an arithmetic number, because the mean of its divisors is an integer number (109146240).

Almost surely, 2^643962639 is an apocalyptic number.

643962639 is a deficient number, since it is larger than the sum of its proper divisors (229207281).

643962639 is a wasteful number, since it uses less digits than its factorization.

643962639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3638269.

The product of its digits is 1259712, while the sum is 48.

The square root of 643962639 is about 25376.4189554003. The cubic root of 643962639 is about 863.5488109042.

The spelling of 643962639 in words is "six hundred forty-three million, nine hundred sixty-two thousand, six hundred thirty-nine".