643004004521 has 4 divisors (see below), whose sum is σ = 645811882500. Its totient is φ = 640196126544.

The previous prime is 643004004427. The next prime is 643004004611. The reversal of 643004004521 is 125400400346.

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 498916195600 + 144087808921 = 706340^2 + 379589^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643004004521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643004004121) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1403938646 + ... + 1403939103.

It is an arithmetic number, because the mean of its divisors is an integer number (161452970625).

Almost surely, 2^643004004521 is an apocalyptic number.

It is an amenable number.

643004004521 is a deficient number, since it is larger than the sum of its proper divisors (2807877979).

643004004521 is a wasteful number, since it uses less digits than its factorization.

643004004521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2807877978.

The product of its (nonzero) digits is 11520, while the sum is 29.

Adding to 643004004521 its reverse (125400400346), we get a palindrome (768404404867).

The spelling of 643004004521 in words is "six hundred forty-three billion, four million, four thousand, five hundred twenty-one".