643521311 has 2 divisors, whose sum is σ = 643521312. Its totient is φ = 643521310.

The previous prime is 643521271. The next prime is 643521323. The reversal of 643521311 is 113125346.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643521311 is a prime.

It is a super-2 number, since 2×643521311² = 828239355422317442, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643521331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321760655 + 321760656.

It is an arithmetic number, because the mean of its divisors is an integer number (321760656).

Almost surely, 2^643521311 is an apocalyptic number.

643521311 is a deficient number, since it is larger than the sum of its proper divisors (1).

643521311 is an equidigital number, since it uses as much as digits as its factorization.

643521311 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 26.

The square root of 643521311 is about 25367.7218330697. The cubic root of 643521311 is about 863.3514933677.

Adding to 643521311 its reverse (113125346), we get a palindrome (756646657).

The spelling of 643521311 in words is "six hundred forty-three million, five hundred twenty-one thousand, three hundred eleven".