644551643223 has 6 divisors (see below), whose sum is σ = 931019040224. Its totient is φ = 429701095476.

The previous prime is 644551643213. The next prime is 644551643269. The reversal of 644551643223 is 322346155446.

644551643223 is a `hidden beast` number, since 6 + 4 + 4 + 551 + 64 + 32 + 2 + 3 = 666.

It is not a de Polignac number, because 644551643223 - 2⁴ = 644551643207 is a prime.

It is a super-3 number, since 3×644551643223³ (a number of 36 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644551643213) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35808424615 + ... + 35808424632.

Almost surely, 2^644551643223 is an apocalyptic number.

644551643223 is a deficient number, since it is larger than the sum of its proper divisors (286467397001).

644551643223 is a wasteful number, since it uses less digits than its factorization.

644551643223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71616849253 (or 71616849250 counting only the distinct ones).

The product of its digits is 2073600, while the sum is 45.

Adding to 644551643223 its reverse (322346155446), we get a palindrome (966897798669).

The spelling of 644551643223 in words is "six hundred forty-four billion, five hundred fifty-one million, six hundred forty-three thousand, two hundred twenty-three".