644642643 has 8 divisors (see below), whose sum is σ = 896894208. Its totient is φ = 411076424.

The previous prime is 644642639. The next prime is 644642671. The reversal of 644642643 is 346246446.

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

It is not a de Polignac number, because 644642643 - 2² = 644642639 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644642143) 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 7 ways as a sum of consecutive naturals, for example, 4671255 + ... + 4671392.

It is an arithmetic number, because the mean of its divisors is an integer number (112111776).

Almost surely, 2^644642643 is an apocalyptic number.

644642643 is a deficient number, since it is larger than the sum of its proper divisors (252251565).

644642643 is a wasteful number, since it uses less digits than its factorization.

644642643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9342673.

The product of its digits is 331776, while the sum is 39.

The square root of 644642643 is about 25389.8137645789. The cubic root of 644642643 is about 863.8526639733.

The spelling of 644642643 in words is "six hundred forty-four million, six hundred forty-two thousand, six hundred forty-three".