643526971 has 4 divisors (see below), whose sum is σ = 651280392. Its totient is φ = 635773552.

The previous prime is 643526963. The next prime is 643526987. The reversal of 643526971 is 179625346.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 643526971 - 2³ = 643526963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643526911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3876586 + ... + 3876751.

It is an arithmetic number, because the mean of its divisors is an integer number (162820098).

Almost surely, 2^643526971 is an apocalyptic number.

643526971 is a deficient number, since it is larger than the sum of its proper divisors (7753421).

643526971 is an equidigital number, since it uses as much as digits as its factorization.

643526971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7753420.

The product of its digits is 272160, while the sum is 43.

The square root of 643526971 is about 25367.8333919158. The cubic root of 643526971 is about 863.3540245219.

The spelling of 643526971 in words is "six hundred forty-three million, five hundred twenty-six thousand, nine hundred seventy-one".