643970441 has 4 divisors (see below), whose sum is σ = 645500484. Its totient is φ = 642440400.

The previous prime is 643970419. The next prime is 643970479. The reversal of 643970441 is 144079346.

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

It can be written as a sum of positive squares in 2 ways, for example, as 149352841 + 494617600 = 12221^2 + 22240^2 .

It is a cyclic number.

It is not a de Polignac number, because 643970441 - 2⁶ = 643970377 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643970395 and 643970404.

It is not an unprimeable number, because it can be changed into a prime (643970141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 764390 + ... + 765231.

It is an arithmetic number, because the mean of its divisors is an integer number (161375121).

Almost surely, 2^643970441 is an apocalyptic number.

It is an amenable number.

643970441 is a deficient number, since it is larger than the sum of its proper divisors (1530043).

643970441 is a wasteful number, since it uses less digits than its factorization.

643970441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1530042.

The product of its (nonzero) digits is 72576, while the sum is 38.

The square root of 643970441 is about 25376.5726803286. The cubic root of 643970441 is about 863.5522983636.

The spelling of 643970441 in words is "six hundred forty-three million, nine hundred seventy thousand, four hundred forty-one".