644007001 has 16 divisors (see below), whose sum is σ = 725313600. Its totient is φ = 566737920.

The previous prime is 644006963. The next prime is 644007029. The reversal of 644007001 is 100700446.

It is a cyclic number.

It is not a de Polignac number, because 644007001 - 2¹³ = 643998809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644007041) 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 15 ways as a sum of consecutive naturals, for example, 47425 + ... + 59473.

It is an arithmetic number, because the mean of its divisors is an integer number (45332100).

Almost surely, 2^644007001 is an apocalyptic number.

It is an amenable number.

644007001 is a deficient number, since it is larger than the sum of its proper divisors (81306599).

644007001 is a wasteful number, since it uses less digits than its factorization.

644007001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12216.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 644007001 is about 25377.2930195480. The cubic root of 644007001 is about 863.5686401460.

Adding to 644007001 its reverse (100700446), we get a palindrome (744707447).

The spelling of 644007001 in words is "six hundred forty-four million, seven thousand, one".