643721379 has 48 divisors (see below), whose sum is σ = 1018054656. Its totient is φ = 360696000.

The previous prime is 643721369. The next prime is 643721399. The reversal of 643721379 is 973127346.

643721379 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 643721379 - 2⁵ = 643721347 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643721379.

It is not an unprimeable number, because it can be changed into a prime (643721339) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2835664 + ... + 2835890.

It is an arithmetic number, because the mean of its divisors is an integer number (21209472).

Almost surely, 2^643721379 is an apocalyptic number.

643721379 is a deficient number, since it is larger than the sum of its proper divisors (374333277).

643721379 is a wasteful number, since it uses less digits than its factorization.

643721379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 536 (or 529 counting only the distinct ones).

The product of its digits is 190512, while the sum is 42.

The square root of 643721379 is about 25371.6648842759. The cubic root of 643721379 is about 863.4409548491.

The spelling of 643721379 in words is "six hundred forty-three million, seven hundred twenty-one thousand, three hundred seventy-nine".