18021944 has 8 divisors (see below), whose sum is σ = 33791160. Its totient is φ = 9010968.

The previous prime is 18021907. The next prime is 18021947. The reversal of 18021944 is 44912081.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18021947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1126364 + ... + 1126379.

It is an arithmetic number, because the mean of its divisors is an integer number (4223895).

Almost surely, 2^18021944 is an apocalyptic number.

It is an amenable number.

18021944 is a deficient number, since it is larger than the sum of its proper divisors (15769216).

18021944 is a wasteful number, since it uses less digits than its factorization.

18021944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2252749 (or 2252745 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 18021944 is about 4245.2260246069. The cubic root of 18021944 is about 262.1805953372.

The spelling of 18021944 in words is "eighteen million, twenty-one thousand, nine hundred forty-four".