644330401 has 8 divisors (see below), whose sum is σ = 756975744. Its totient is φ = 540696720.

The previous prime is 644330387. The next prime is 644330419. The reversal of 644330401 is 104033446.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 644330401 - 2¹¹ = 644328353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644330101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2252761 + ... + 2253046.

It is an arithmetic number, because the mean of its divisors is an integer number (94621968).

Almost surely, 2^644330401 is an apocalyptic number.

It is an amenable number.

644330401 is a deficient number, since it is larger than the sum of its proper divisors (112645343).

644330401 is a wasteful number, since it uses less digits than its factorization.

644330401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4505831.

The product of its (nonzero) digits is 3456, while the sum is 25.

The square root of 644330401 is about 25383.6640578148. The cubic root of 644330401 is about 863.7131682659.

Adding to 644330401 its reverse (104033446), we get a palindrome (748363847).

The spelling of 644330401 in words is "six hundred forty-four million, three hundred thirty thousand, four hundred one".