643949751593 has 4 divisors (see below), whose sum is σ = 645981139140. Its totient is φ = 641918364048.

The previous prime is 643949751551. The next prime is 643949751611. The reversal of 643949751593 is 395157949346.

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 220704523264 + 423245228329 = 469792^2 + 650573^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643949751593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643949751293) 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, 1015693298 + ... + 1015693931.

It is an arithmetic number, because the mean of its divisors is an integer number (161495284785).

Almost surely, 2^643949751593 is an apocalyptic number.

It is an amenable number.

643949751593 is a deficient number, since it is larger than the sum of its proper divisors (2031387547).

643949751593 is a wasteful number, since it uses less digits than its factorization.

643949751593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2031387546.

The product of its digits is 110224800, while the sum is 65.

The spelling of 643949751593 in words is "six hundred forty-three billion, nine hundred forty-nine million, seven hundred fifty-one thousand, five hundred ninety-three".