1644262651321 has 2 divisors, whose sum is σ = 1644262651322. Its totient is φ = 1644262651320.

The previous prime is 1644262651313. The next prime is 1644262651333. The reversal of 1644262651321 is 1231562624461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1374474864400 + 269787786921 = 1172380^2 + 519411^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644262651321 - 2³ = 1644262651313 is a prime.

It is a super-3 number, since 3×1644262651321³ (a number of 38 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1644262951321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822131325660 + 822131325661.

It is an arithmetic number, because the mean of its divisors is an integer number (822131325661).

Almost surely, 2^{1644262651321} is an apocalyptic number.

It is an amenable number.

1644262651321 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644262651321 is an equidigital number, since it uses as much as digits as its factorization.

1644262651321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 414720, while the sum is 43.

The spelling of 1644262651321 in words is "one trillion, six hundred forty-four billion, two hundred sixty-two million, six hundred fifty-one thousand, three hundred twenty-one".