643126655165 has 4 divisors (see below), whose sum is σ = 771751986204. Its totient is φ = 514501324128.

The previous prime is 643126655161. The next prime is 643126655183. The reversal of 643126655165 is 561556621346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 466972689316 + 176153965849 = 683354^2 + 419707^2 .

It is a cyclic number.

It is not a de Polignac number, because 643126655165 - 2² = 643126655161 is a prime.

It is a super-2 number, since 2×643126655165² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643126655161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64312665512 + ... + 64312665521.

It is an arithmetic number, because the mean of its divisors is an integer number (192937996551).

Almost surely, 2^643126655165 is an apocalyptic number.

It is an amenable number.

643126655165 is a deficient number, since it is larger than the sum of its proper divisors (128625331039).

643126655165 is a wasteful number, since it uses less digits than its factorization.

643126655165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128625331038.

The product of its digits is 3888000, while the sum is 50.

The spelling of 643126655165 in words is "six hundred forty-three billion, one hundred twenty-six million, six hundred fifty-five thousand, one hundred sixty-five".