18384021 has 12 divisors (see below), whose sum is σ = 28116972. Its totient is φ = 11534976.

The previous prime is 18384007. The next prime is 18384043. The reversal of 18384021 is 12048381.

It can be written as a sum of positive squares in 2 ways, for example, as 16719921 + 1664100 = 4089^2 + 1290^2 .

It is not a de Polignac number, because 18384021 - 2¹¹ = 18381973 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18384221) 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, 59926 + ... + 60231.

It is an arithmetic number, because the mean of its divisors is an integer number (2343081).

Almost surely, 2^18384021 is an apocalyptic number.

It is an amenable number.

18384021 is a deficient number, since it is larger than the sum of its proper divisors (9732951).

18384021 is a wasteful number, since it uses less digits than its factorization.

18384021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120180 (or 120177 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 18384021 is about 4287.6591515651. The cubic root of 18384021 is about 263.9247805676.

It can be divided in two parts, 1838402 and 1, that added together give a triangular number (1838403 = T₁₉₁₇).

The spelling of 18384021 in words is "eighteen million, three hundred eighty-four thousand, twenty-one".