644499001 has 4 divisors (see below), whose sum is σ = 644729332. Its totient is φ = 644268672.

The previous prime is 644498999. The next prime is 644499029. The reversal of 644499001 is 100994446.

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 151880976 + 492618025 = 12324^2 + 22195^2 .

It is a cyclic number.

It is not a de Polignac number, because 644499001 - 2¹ = 644498999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644499091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110916 + ... + 116581.

It is an arithmetic number, because the mean of its divisors is an integer number (161182333).

Almost surely, 2^644499001 is an apocalyptic number.

It is an amenable number.

644499001 is a deficient number, since it is larger than the sum of its proper divisors (230331).

644499001 is a wasteful number, since it uses less digits than its factorization.

644499001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230330.

The product of its (nonzero) digits is 31104, while the sum is 37.

The square root of 644499001 is about 25386.9848741437. The cubic root of 644499001 is about 863.7884967724.

The spelling of 644499001 in words is "six hundred forty-four million, four hundred ninety-nine thousand, one".