644077543 has 2 divisors, whose sum is σ = 644077544. Its totient is φ = 644077542.

The previous prime is 644077531. The next prime is 644077573. The reversal of 644077543 is 345770446.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644077543 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644077496 and 644077505.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644077573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322038771 + 322038772.

It is an arithmetic number, because the mean of its divisors is an integer number (322038772).

Almost surely, 2^644077543 is an apocalyptic number.

644077543 is a deficient number, since it is larger than the sum of its proper divisors (1).

644077543 is an equidigital number, since it uses as much as digits as its factorization.

644077543 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 282240, while the sum is 40.

The square root of 644077543 is about 25378.6828460423. The cubic root of 644077543 is about 863.6001696350.

The spelling of 644077543 in words is "six hundred forty-four million, seventy-seven thousand, five hundred forty-three".