644421474250321 has 2 divisors, whose sum is σ = 644421474250322. Its totient is φ = 644421474250320.

The previous prime is 644421474250303. The next prime is 644421474250339. The reversal of 644421474250321 is 123052474124446.

It is a balanced prime because it is at equal distance from previous prime (644421474250303) and next prime (644421474250339).

It can be written as a sum of positive squares in only one way, i.e., 517041019423296 + 127380454827025 = 22738536^2 + 11286295^2 .

It is a cyclic number.

It is not a de Polignac number, because 644421474250321 - 2²¹ = 644421472153169 is a prime.

It is not a weakly prime, because it can be changed into another prime (644421474650321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322210737125160 + 322210737125161.

It is an arithmetic number, because the mean of its divisors is an integer number (322210737125161).

Almost surely, 2^{644421474250321} is an apocalyptic number.

It is an amenable number.

644421474250321 is a deficient number, since it is larger than the sum of its proper divisors (1).

644421474250321 is an equidigital number, since it uses as much as digits as its factorization.

644421474250321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5160960, while the sum is 49.

The spelling of 644421474250321 in words is "six hundred forty-four trillion, four hundred twenty-one billion, four hundred seventy-four million, two hundred fifty thousand, three hundred twenty-one".