644001022 has 40 divisors (see below), whose sum is σ = 1154773872. Its totient is φ = 269186400.

The previous prime is 644001019. The next prime is 644001023. The reversal of 644001022 is 220100446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644001023) 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 19 ways as a sum of consecutive naturals, for example, 195247 + ... + 198517.

Almost surely, 2^644001022 is an apocalyptic number.

644001022 is a deficient number, since it is larger than the sum of its proper divisors (510772850).

644001022 is an equidigital number, since it uses as much as digits as its factorization.

644001022 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3342 (or 3321 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 644001022 is about 25377.1752171119. The cubic root of 644001022 is about 863.5659676633.

Adding to 644001022 its reverse (220100446), we get a palindrome (864101468).

The spelling of 644001022 in words is "six hundred forty-four million, one thousand, twenty-two".