644932879 has 2 divisors, whose sum is σ = 644932880. Its totient is φ = 644932878.

The previous prime is 644932867. The next prime is 644932889. The reversal of 644932879 is 978239446.

It is a happy number.

644932879 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644932879 - 2⁹ = 644932367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644932819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322466439 + 322466440.

It is an arithmetic number, because the mean of its divisors is an integer number (322466440).

Almost surely, 2^644932879 is an apocalyptic number.

644932879 is a deficient number, since it is larger than the sum of its proper divisors (1).

644932879 is an equidigital number, since it uses as much as digits as its factorization.

644932879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2612736, while the sum is 52.

The square root of 644932879 is about 25395.5287206232. The cubic root of 644932879 is about 863.9822879992.

The spelling of 644932879 in words is "six hundred forty-four million, nine hundred thirty-two thousand, eight hundred seventy-nine".