644216371 has 2 divisors, whose sum is σ = 644216372. Its totient is φ = 644216370.

The previous prime is 644216347. The next prime is 644216381. The reversal of 644216371 is 173612446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644216371 - 2¹⁹ = 643692083 is a prime.

It is not a weakly prime, because it can be changed into another prime (644216381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322108185 + 322108186.

It is an arithmetic number, because the mean of its divisors is an integer number (322108186).

Almost surely, 2^644216371 is an apocalyptic number.

644216371 is a deficient number, since it is larger than the sum of its proper divisors (1).

644216371 is an equidigital number, since it uses as much as digits as its factorization.

644216371 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 34.

The square root of 644216371 is about 25381.4178287975. The cubic root of 644216371 is about 863.6622135471.

The spelling of 644216371 in words is "six hundred forty-four million, two hundred sixteen thousand, three hundred seventy-one".