643521297 has 4 divisors (see below), whose sum is σ = 858028400. Its totient is φ = 429014196.

The previous prime is 643521271. The next prime is 643521311. The reversal of 643521297 is 792125346.

643521297 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 643521297 - 2⁶ = 643521233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643521217) 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, 107253547 + ... + 107253552.

It is an arithmetic number, because the mean of its divisors is an integer number (214507100).

Almost surely, 2^643521297 is an apocalyptic number.

It is an amenable number.

643521297 is a deficient number, since it is larger than the sum of its proper divisors (214507103).

643521297 is a wasteful number, since it uses less digits than its factorization.

643521297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214507102.

The product of its digits is 90720, while the sum is 39.

The square root of 643521297 is about 25367.7215571285. The cubic root of 643521297 is about 863.3514871069.

The spelling of 643521297 in words is "six hundred forty-three million, five hundred twenty-one thousand, two hundred ninety-seven".