644722001 has 12 divisors (see below), whose sum is σ = 809899776. Its totient is φ = 502380120.

The previous prime is 644721943. The next prime is 644722019. The reversal of 644722001 is 100227446.

It is not a de Polignac number, because 644722001 - 2⁶ = 644721937 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644722031) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 379745 + ... + 381438.

It is an arithmetic number, because the mean of its divisors is an integer number (67491648).

Almost surely, 2^644722001 is an apocalyptic number.

It is an amenable number.

644722001 is a deficient number, since it is larger than the sum of its proper divisors (165177775).

644722001 is a wasteful number, since it uses less digits than its factorization.

644722001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 761212 (or 761201 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 26.

The square root of 644722001 is about 25391.3765085708. The cubic root of 644722001 is about 863.8881103857. Note that the first 3 decimals are identical.

Adding to 644722001 its reverse (100227446), we get a palindrome (744949447).

The spelling of 644722001 in words is "six hundred forty-four million, seven hundred twenty-two thousand, one".