644153443 has 4 divisors (see below), whose sum is σ = 682044840. Its totient is φ = 606262048.

The previous prime is 644153407. The next prime is 644153483. The reversal of 644153443 is 344351446.

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 644153443 - 2⁹ = 644152931 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644153399 and 644153408.

It is not an unprimeable number, because it can be changed into a prime (644153483) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18945673 + ... + 18945706.

It is an arithmetic number, because the mean of its divisors is an integer number (170511210).

Almost surely, 2^644153443 is an apocalyptic number.

644153443 is a deficient number, since it is larger than the sum of its proper divisors (37891397).

644153443 is a wasteful number, since it uses less digits than its factorization.

644153443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37891396.

The product of its digits is 69120, while the sum is 34.

The square root of 644153443 is about 25380.1781514630. The cubic root of 644153443 is about 863.6340913675.

The spelling of 644153443 in words is "six hundred forty-four million, one hundred fifty-three thousand, four hundred forty-three".