644732543 has 24 divisors (see below), whose sum is σ = 809459280. Its totient is φ = 508999680.

The previous prime is 644732537. The next prime is 644732597. The reversal of 644732543 is 345237446.

It is not a de Polignac number, because 644732543 - 2²⁰ = 643683967 is a prime.

Its product of digits (241920) is a multiple of the sum of its prime divisors (2240).

It is a junction number, because it is equal to n+sod(n) for n = 644732497 and 644732506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646732543) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 407528 + ... + 409106.

It is an arithmetic number, because the mean of its divisors is an integer number (33727470).

Almost surely, 2^644732543 is an apocalyptic number.

644732543 is a deficient number, since it is larger than the sum of its proper divisors (164726737).

644732543 is a wasteful number, since it uses less digits than its factorization.

644732543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2247 (or 2240 counting only the distinct ones).

The product of its digits is 241920, while the sum is 38.

The square root of 644732543 is about 25391.5840978857. The cubic root of 644732543 is about 863.8928189054.

Adding to 644732543 its reverse (345237446), we get a palindrome (989969989).

The spelling of 644732543 in words is "six hundred forty-four million, seven hundred thirty-two thousand, five hundred forty-three".