643602653 has 4 divisors (see below), whose sum is σ = 643947420. Its totient is φ = 643257888.

The previous prime is 643602647. The next prime is 643602683. The reversal of 643602653 is 356206346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 356206346 = 2 ⋅178103173.

It can be written as a sum of positive squares in 2 ways, for example, as 152448409 + 491154244 = 12347^2 + 22162^2 .

It is a cyclic number.

It is not a de Polignac number, because 643602653 - 2⁸ = 643602397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643602623) 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, 169568 + ... + 173321.

It is an arithmetic number, because the mean of its divisors is an integer number (160986855).

Almost surely, 2^643602653 is an apocalyptic number.

It is an amenable number.

643602653 is a deficient number, since it is larger than the sum of its proper divisors (344767).

643602653 is a wasteful number, since it uses less digits than its factorization.

643602653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344766.

The product of its (nonzero) digits is 77760, while the sum is 35.

The square root of 643602653 is about 25369.3250402923. The cubic root of 643602653 is about 863.3878681167.

Adding to 643602653 its reverse (356206346), we get a palindrome (999808999).

The spelling of 643602653 in words is "six hundred forty-three million, six hundred two thousand, six hundred fifty-three".