643900765 has 8 divisors (see below), whose sum is σ = 773352288. Its totient is φ = 514673040.

The previous prime is 643900757. The next prime is 643900771. The reversal of 643900765 is 567009346.

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

It is not a de Polignac number, because 643900765 - 2³ = 643900757 is a prime.

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 7 ways as a sum of consecutive naturals, for example, 49551 + ... + 61180.

It is an arithmetic number, because the mean of its divisors is an integer number (96669036).

Almost surely, 2^643900765 is an apocalyptic number.

It is an amenable number.

643900765 is a deficient number, since it is larger than the sum of its proper divisors (129451523).

643900765 is a wasteful number, since it uses less digits than its factorization.

643900765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111899.

The product of its (nonzero) digits is 136080, while the sum is 40.

The square root of 643900765 is about 25375.1998021690. The cubic root of 643900765 is about 863.5211525033.

The spelling of 643900765 in words is "six hundred forty-three million, nine hundred thousand, seven hundred sixty-five".