644342420456213 has 4 divisors (see below), whose sum is σ = 647016040458348. Its totient is φ = 641668800454080.

The previous prime is 644342420456177. The next prime is 644342420456249. The reversal of 644342420456213 is 312654024243446.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (644342420456177) and next prime (644342420456249).

It can be written as a sum of positive squares in 2 ways, for example, as 599328076267684 + 45014344188529 = 24481178^2 + 6709273^2 .

It is a cyclic number.

It is not a de Polignac number, because 644342420456213 - 2¹⁴ = 644342420439829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644342420456113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1336810000706 + ... + 1336810001187.

It is an arithmetic number, because the mean of its divisors is an integer number (161754010114587).

Almost surely, 2^{644342420456213} is an apocalyptic number.

It is an amenable number.

644342420456213 is a deficient number, since it is larger than the sum of its proper divisors (2673620002135).

644342420456213 is a wasteful number, since it uses less digits than its factorization.

644342420456213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2673620002134.

The product of its (nonzero) digits is 13271040, while the sum is 50.

Adding to 644342420456213 its reverse (312654024243446), we get a palindrome (956996444699659).

The spelling of 644342420456213 in words is "six hundred forty-four trillion, three hundred forty-two billion, four hundred twenty million, four hundred fifty-six thousand, two hundred thirteen".