644342121243413 has 2 divisors, whose sum is σ = 644342121243414. Its totient is φ = 644342121243412.

The previous prime is 644342121243397. The next prime is 644342121243467. The reversal of 644342121243413 is 314342121243446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644305725379684 + 36395863729 = 25383178^2 + 190777^2 .

It is a cyclic number.

It is not a de Polignac number, because 644342121243413 - 2⁴ = 644342121243397 is a prime.

It is a super-2 number, since 2×644342121243413² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644342121243013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322171060621706 + 322171060621707.

It is an arithmetic number, because the mean of its divisors is an integer number (322171060621707).

Almost surely, 2^{644342121243413} is an apocalyptic number.

It is an amenable number.

644342121243413 is a deficient number, since it is larger than the sum of its proper divisors (1).

644342121243413 is an equidigital number, since it uses as much as digits as its factorization.

644342121243413 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1327104, while the sum is 44.

Adding to 644342121243413 its reverse (314342121243446), we get a palindrome (958684242486859).

The spelling of 644342121243413 in words is "six hundred forty-four trillion, three hundred forty-two billion, one hundred twenty-one million, two hundred forty-three thousand, four hundred thirteen".