643311666221065 has 8 divisors (see below), whose sum is σ = 771975402057288. Its totient is φ = 514648397915520.

The previous prime is 643311666221053. The next prime is 643311666221167. The reversal of 643311666221065 is 560122666113346.

It can be written as a sum of positive squares in 4 ways, for example, as 130697871988489 + 512613794232576 = 11432317^2 + 22640976^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 643311666221065 - 2⁴⁵ = 608127294132233 is a prime.

It is a super-2 number, since 2×643311666221065² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 113848356 + ... + 119365285.

It is an arithmetic number, because the mean of its divisors is an integer number (96496925257161).

Almost surely, 2^{643311666221065} is an apocalyptic number.

It is an amenable number.

643311666221065 is a deficient number, since it is larger than the sum of its proper divisors (128663735836223).

643311666221065 is a wasteful number, since it uses less digits than its factorization.

643311666221065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233765339.

The product of its (nonzero) digits is 5598720, while the sum is 52.

The spelling of 643311666221065 in words is "six hundred forty-three trillion, three hundred eleven billion, six hundred sixty-six million, two hundred twenty-one thousand, sixty-five".