1643817658729 has 2 divisors, whose sum is σ = 1643817658730. Its totient is φ = 1643817658728.

The previous prime is 1643817658727. The next prime is 1643817658733. The reversal of 1643817658729 is 9278567183461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1608838560000 + 34979098729 = 1268400^2 + 187027^2 .

It is an emirp because it is prime and its reverse (9278567183461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1643817658729 - 2¹ = 1643817658727 is a prime.

It is a super-2 number, since 2×1643817658729² (a number of 25 digits) contains 22 as substring.

Together with 1643817658727, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1643817658727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821908829364 + 821908829365.

It is an arithmetic number, because the mean of its divisors is an integer number (821908829365).

Almost surely, 2^{1643817658729} is an apocalyptic number.

It is an amenable number.

1643817658729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643817658729 is an equidigital number, since it uses as much as digits as its factorization.

1643817658729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 121927680, while the sum is 67.

The spelling of 1643817658729 in words is "one trillion, six hundred forty-three billion, eight hundred seventeen million, six hundred fifty-eight thousand, seven hundred twenty-nine".