643440503 has 4 divisors (see below), whose sum is σ = 645350160. Its totient is φ = 641530848.

The previous prime is 643440493. The next prime is 643440509. The reversal of 643440503 is 305044346.

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 643440503 - 2⁶ = 643440439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643440509) 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, 954323 + ... + 954996.

It is an arithmetic number, because the mean of its divisors is an integer number (161337540).

Almost surely, 2^643440503 is an apocalyptic number.

643440503 is a deficient number, since it is larger than the sum of its proper divisors (1909657).

643440503 is a wasteful number, since it uses less digits than its factorization.

643440503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1909656.

The product of its (nonzero) digits is 17280, while the sum is 29.

The square root of 643440503 is about 25366.1290503695. The cubic root of 643440503 is about 863.3153543791.

Adding to 643440503 its reverse (305044346), we get a palindrome (948484849).

The spelling of 643440503 in words is "six hundred forty-three million, four hundred forty thousand, five hundred three".