18000644 has 6 divisors (see below), whose sum is σ = 31501134. Its totient is φ = 9000320.

The previous prime is 18000643. The next prime is 18000649. The reversal of 18000644 is 44600081.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17960644 + 40000 = 4238^2 + 200^2 .

It is not an unprimeable number, because it can be changed into a prime (18000643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2250077 + ... + 2250084.

It is an arithmetic number, because the mean of its divisors is an integer number (5250189).

Almost surely, 2^18000644 is an apocalyptic number.

It is an amenable number.

18000644 is a deficient number, since it is larger than the sum of its proper divisors (13500490).

18000644 is a wasteful number, since it uses less digits than its factorization.

18000644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4500165 (or 4500163 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 18000644 is about 4242.7165825683. The cubic root of 18000644 is about 262.0772648604.

The spelling of 18000644 in words is "eighteen million, six hundred forty-four", and thus it is an aban number.