643907 has 4 divisors (see below), whose sum is σ = 702456. Its totient is φ = 585360.

The previous prime is 643889. The next prime is 643919. The reversal of 643907 is 709346.

643907 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 643907 - 2⁸ = 643651 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 643907.

It is not an unprimeable number, because it can be changed into a prime (643927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29258 + ... + 29279.

It is an arithmetic number, because the mean of its divisors is an integer number (175614).

2⁶⁴³⁹⁰⁷ is an apocalyptic number.

643907 is a deficient number, since it is larger than the sum of its proper divisors (58549).

643907 is a wasteful number, since it uses less digits than its factorization.

643907 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58548.

The product of its (nonzero) digits is 4536, while the sum is 29.

The square root of 643907 is about 802.4381596111. The cubic root of 643907 is about 86.3523939701.

The spelling of 643907 in words is "six hundred forty-three thousand, nine hundred seven".