643391975 has 12 divisors (see below), whose sum is σ = 800183904. Its totient is φ = 513179520.

The previous prime is 643391933. The next prime is 643391993. The reversal of 643391975 is 579193346.

643391975 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 643391975 - 2¹² = 643387879 is a prime.

It is a hoax number, since the sum of its digits (47) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29759 + ... + 46608.

It is an arithmetic number, because the mean of its divisors is an integer number (66681992).

Almost surely, 2^643391975 is an apocalyptic number.

643391975 is a deficient number, since it is larger than the sum of its proper divisors (156791929).

643391975 is a wasteful number, since it uses less digits than its factorization.

643391975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76714 (or 76709 counting only the distinct ones).

The product of its digits is 612360, while the sum is 47.

The square root of 643391975 is about 25365.1724811798. The cubic root of 643391975 is about 863.2936502119.

The spelling of 643391975 in words is "six hundred forty-three million, three hundred ninety-one thousand, nine hundred seventy-five".