643655544145 has 4 divisors (see below), whose sum is σ = 772386652980. Its totient is φ = 514924435312.

The previous prime is 643655544143. The next prime is 643655544167. The reversal of 643655544145 is 541445556346.

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 439234911504 + 204420632641 = 662748^2 + 452129^2 .

It is a cyclic number.

It is not a de Polignac number, because 643655544145 - 2¹ = 643655544143 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643655544092 and 643655544101.

It is not an unprimeable number, because it can be changed into a prime (643655544143) 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, 64365554410 + ... + 64365554419.

It is an arithmetic number, because the mean of its divisors is an integer number (193096663245).

Almost surely, 2^643655544145 is an apocalyptic number.

It is an amenable number.

643655544145 is a deficient number, since it is larger than the sum of its proper divisors (128731108835).

643655544145 is a wasteful number, since it uses less digits than its factorization.

643655544145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128731108834.

The product of its digits is 17280000, while the sum is 52.

The spelling of 643655544145 in words is "six hundred forty-three billion, six hundred fifty-five million, five hundred forty-four thousand, one hundred forty-five".