644297783 has 2 divisors, whose sum is σ = 644297784. Its totient is φ = 644297782.

The previous prime is 644297779. The next prime is 644297833. The reversal of 644297783 is 387792446.

It is an a-pointer prime, because the next prime (644297833) can be obtained adding 644297783 to its sum of digits (50).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644297783 - 2² = 644297779 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644297713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322148891 + 322148892.

It is an arithmetic number, because the mean of its divisors is an integer number (322148892).

Almost surely, 2^644297783 is an apocalyptic number.

644297783 is a deficient number, since it is larger than the sum of its proper divisors (1).

644297783 is an equidigital number, since it uses as much as digits as its factorization.

644297783 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2032128, while the sum is 50.

The square root of 644297783 is about 25383.0215498471. The cubic root of 644297783 is about 863.6985934083.

The spelling of 644297783 in words is "six hundred forty-four million, two hundred ninety-seven thousand, seven hundred eighty-three".