643994374 has 8 divisors (see below), whose sum is σ = 1022814648. Its totient is φ = 303056160.

The previous prime is 643994363. The next prime is 643994399. The reversal of 643994374 is 473499346.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9470472 + ... + 9470539.

It is an arithmetic number, because the mean of its divisors is an integer number (127851831).

Almost surely, 2^643994374 is an apocalyptic number.

643994374 is a deficient number, since it is larger than the sum of its proper divisors (378820274).

643994374 is a wasteful number, since it uses less digits than its factorization.

643994374 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18941030.

The product of its digits is 1959552, while the sum is 49.

The square root of 643994374 is about 25377.0442329283. The cubic root of 643994374 is about 863.5629961326.

The spelling of 643994374 in words is "six hundred forty-three million, nine hundred ninety-four thousand, three hundred seventy-four".