644156983 has 2 divisors, whose sum is σ = 644156984. Its totient is φ = 644156982.

The previous prime is 644156977. The next prime is 644157049. The reversal of 644156983 is 389651446.

644156983 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644156983 - 2¹⁷ = 644025911 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644156923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322078491 + 322078492.

It is an arithmetic number, because the mean of its divisors is an integer number (322078492).

Almost surely, 2^644156983 is an apocalyptic number.

644156983 is a deficient number, since it is larger than the sum of its proper divisors (1).

644156983 is an equidigital number, since it uses as much as digits as its factorization.

644156983 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 622080, while the sum is 46.

The square root of 644156983 is about 25380.2478908304. The cubic root of 644156983 is about 863.6356734228.

The spelling of 644156983 in words is "six hundred forty-four million, one hundred fifty-six thousand, nine hundred eighty-three".