643425331 has 4 divisors (see below), whose sum is σ = 643517200. Its totient is φ = 643333464.

The previous prime is 643425311. The next prime is 643425337. The reversal of 643425331 is 133524346.

643425331 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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643425331 is a prime.

It is a super-2 number, since 2×643425331² = 827992313144919122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643425293 and 643425302.

It is not an unprimeable number, because it can be changed into a prime (643425337) 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, 34476 + ... + 49753.

It is an arithmetic number, because the mean of its divisors is an integer number (160879300).

Almost surely, 2^643425331 is an apocalyptic number.

643425331 is a deficient number, since it is larger than the sum of its proper divisors (91869).

643425331 is an equidigital number, since it uses as much as digits as its factorization.

643425331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91868.

The product of its digits is 25920, while the sum is 31.

The square root of 643425331 is about 25365.8299883919. The cubic root of 643425331 is about 863.3085688134.

Adding to 643425331 its reverse (133524346), we get a palindrome (776949677).

The spelling of 643425331 in words is "six hundred forty-three million, four hundred twenty-five thousand, three hundred thirty-one".