18228021 has 16 divisors (see below), whose sum is σ = 27875328. Its totient is φ = 10378800.

The previous prime is 18228017. The next prime is 18228059. The reversal of 18228021 is 12082281.

It is not a de Polignac number, because 18228021 - 2² = 18228017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18227982 and 18228000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18228061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5136 + ... + 7926.

It is an arithmetic number, because the mean of its divisors is an integer number (1742208).

Almost surely, 2^18228021 is an apocalyptic number.

It is an amenable number.

18228021 is a deficient number, since it is larger than the sum of its proper divisors (9647307).

18228021 is a wasteful number, since it uses less digits than its factorization.

18228021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3112.

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 18228021 is about 4269.4286502997. The cubic root of 18228021 is about 263.1761363067.

It can be divided in two parts, 182 and 28021, that added together give a triangular number (28203 = T₂₃₇).

The spelling of 18228021 in words is "eighteen million, two hundred twenty-eight thousand, twenty-one".