644220065422461 has 16 divisors (see below), whose sum is σ = 937444927341888. Its totient is φ = 390270753513600.

The previous prime is 644220065422441. The next prime is 644220065422471. The reversal of 644220065422461 is 164224560022446.

It is not a de Polignac number, because 644220065422461 - 2²⁹ = 644219528551549 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644220065422461.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644220065422441) 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 in 15 ways as a sum of consecutive naturals, for example, 4141165360 + ... + 4141320921.

It is an arithmetic number, because the mean of its divisors is an integer number (58590307958868).

Almost surely, 2^{644220065422461} is an apocalyptic number.

It is an amenable number.

644220065422461 is a deficient number, since it is larger than the sum of its proper divisors (293224861919427).

644220065422461 is a wasteful number, since it uses less digits than its factorization.

644220065422461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8282488652.

The product of its (nonzero) digits is 4423680, while the sum is 48.

The spelling of 644220065422461 in words is "six hundred forty-four trillion, two hundred twenty billion, sixty-five million, four hundred twenty-two thousand, four hundred sixty-one".