4000644 has 48 divisors (see below), whose sum is σ = 10987200. Its totient is φ = 1254528.

The previous prime is 4000631. The next prime is 4000649. The reversal of 4000644 is 4460004.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4000649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 747 + ... + 2925.

It is an arithmetic number, because the mean of its divisors is an integer number (228900).

Almost surely, 2^4000644 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 4000644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5493600).

4000644 is an abundant number, since it is smaller than the sum of its proper divisors (6986556).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

4000644 is a wasteful number, since it uses less digits than its factorization.

4000644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2209 (or 2201 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 4000644 is about 2000.1609935203. The cubic root of 4000644 is about 158.7486237920.

Adding to 4000644 its reverse (4460004), we get a palindrome (8460648).

The spelling of 4000644 in words is "four million, six hundred forty-four", and thus it is an aban number.