643581249 has 8 divisors (see below), whose sum is σ = 859378560. Its totient is φ = 428419056.

The previous prime is 643581233. The next prime is 643581269. The reversal of 643581249 is 942185346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 643581249 - 2⁴ = 643581233 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643581249.

It is not an unprimeable number, because it can be changed into a prime (643581229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 156409 + ... + 160470.

It is an arithmetic number, because the mean of its divisors is an integer number (107422320).

Almost surely, 2^643581249 is an apocalyptic number.

It is an amenable number.

643581249 is a deficient number, since it is larger than the sum of its proper divisors (215797311).

643581249 is a wasteful number, since it uses less digits than its factorization.

643581249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 317559.

The product of its digits is 207360, while the sum is 42.

The square root of 643581249 is about 25368.9031887467. The cubic root of 643581249 is about 863.3782969117.

The spelling of 643581249 in words is "six hundred forty-three million, five hundred eighty-one thousand, two hundred forty-nine".