644166463 has 2 divisors, whose sum is σ = 644166464. Its totient is φ = 644166462.

The previous prime is 644166437. The next prime is 644166469. The reversal of 644166463 is 364661446.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644166463 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644166469) 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, 322083231 + 322083232.

It is an arithmetic number, because the mean of its divisors is an integer number (322083232).

Almost surely, 2^644166463 is an apocalyptic number.

644166463 is a deficient number, since it is larger than the sum of its proper divisors (1).

644166463 is an equidigital number, since it uses as much as digits as its factorization.

644166463 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 248832, while the sum is 40.

The square root of 644166463 is about 25380.4346495485. The cubic root of 644166463 is about 863.6399100847.

The spelling of 644166463 in words is "six hundred forty-four million, one hundred sixty-six thousand, four hundred sixty-three".