643634903 has 8 divisors (see below), whose sum is σ = 668368800. Its totient is φ = 619070368.

The previous prime is 643634891. The next prime is 643634939. The reversal of 643634903 is 309436346.

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

It is a cyclic number.

It is not a de Polignac number, because 643634903 - 2²⁴ = 626857687 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643634983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34568 + ... + 49821.

It is an arithmetic number, because the mean of its divisors is an integer number (83546100).

Almost surely, 2^643634903 is an apocalyptic number.

643634903 is a deficient number, since it is larger than the sum of its proper divisors (24733897).

643634903 is a wasteful number, since it uses less digits than its factorization.

643634903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84681.

The product of its (nonzero) digits is 139968, while the sum is 38.

The square root of 643634903 is about 25369.9606424606. The cubic root of 643634903 is about 863.4022889158.

The spelling of 643634903 in words is "six hundred forty-three million, six hundred thirty-four thousand, nine hundred three".