643544623 has 4 divisors (see below), whose sum is σ = 671524848. Its totient is φ = 615564400.

The previous prime is 643544609. The next prime is 643544641. The reversal of 643544623 is 326445346.

It is a happy number.

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 643544623 - 2⁵ = 643544591 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 (643544123) 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, 13990078 + ... + 13990123.

It is an arithmetic number, because the mean of its divisors is an integer number (167881212).

Almost surely, 2^643544623 is an apocalyptic number.

643544623 is a deficient number, since it is larger than the sum of its proper divisors (27980225).

643544623 is a wasteful number, since it uses less digits than its factorization.

643544623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27980224.

The product of its digits is 207360, while the sum is 37.

The square root of 643544623 is about 25368.1813104527. The cubic root of 643544623 is about 863.3619184081.

Adding to 643544623 its reverse (326445346), we get a palindrome (969989969).

The spelling of 643544623 in words is "six hundred forty-three million, five hundred forty-four thousand, six hundred twenty-three".