18855221 has 8 divisors (see below), whose sum is σ = 23507904. Its totient is φ = 14692320.

The previous prime is 18855209. The next prime is 18855233. The reversal of 18855221 is 12255881.

18855221 = T₂₈₃ + T₂₈₄ + ... + T₅₁₃.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18855209) and next prime (18855233).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18855221 - 2⁶ = 18855157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18855821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 122360 + ... + 122513.

It is an arithmetic number, because the mean of its divisors is an integer number (2938488).

Almost surely, 2^18855221 is an apocalyptic number.

18855221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18855221 is a deficient number, since it is larger than the sum of its proper divisors (4652683).

18855221 is a wasteful number, since it uses less digits than its factorization.

18855221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244891.

The product of its digits is 6400, while the sum is 32.

The square root of 18855221 is about 4342.2598954922. The cubic root of 18855221 is about 266.1606666876.

The spelling of 18855221 in words is "eighteen million, eight hundred fifty-five thousand, two hundred twenty-one".