644202642197 has 2 divisors, whose sum is σ = 644202642198. Its totient is φ = 644202642196.

The previous prime is 644202642163. The next prime is 644202642227. The reversal of 644202642197 is 791246202446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 638966817316 + 5235824881 = 799354^2 + 72359^2 .

It is a cyclic number.

It is not a de Polignac number, because 644202642197 - 2⁸ = 644202641941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644202642157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322101321098 + 322101321099.

It is an arithmetic number, because the mean of its divisors is an integer number (322101321099).

Almost surely, 2^644202642197 is an apocalyptic number.

It is an amenable number.

644202642197 is a deficient number, since it is larger than the sum of its proper divisors (1).

644202642197 is an equidigital number, since it uses as much as digits as its factorization.

644202642197 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1161216, while the sum is 47.

The spelling of 644202642197 in words is "six hundred forty-four billion, two hundred two million, six hundred forty-two thousand, one hundred ninety-seven".