18533421 has 8 divisors (see below), whose sum is σ = 27456960. Its totient is φ = 12355596.

The previous prime is 18533413. The next prime is 18533429. The reversal of 18533421 is 12433581.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18533413) and next prime (18533429).

It is not a de Polignac number, because 18533421 - 2³ = 18533413 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 686423 = 18533421 / (1 + 8 + 5 + 3 + 3 + 4 + 2 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18533429) 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, 343185 + ... + 343238.

It is an arithmetic number, because the mean of its divisors is an integer number (3432120).

Almost surely, 2^18533421 is an apocalyptic number.

It is an amenable number.

18533421 is a deficient number, since it is larger than the sum of its proper divisors (8923539).

18533421 is an equidigital number, since it uses as much as digits as its factorization.

18533421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686432 (or 686426 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 18533421 is about 4305.0459927857. The cubic root of 18533421 is about 264.6377916106.

The spelling of 18533421 in words is "eighteen million, five hundred thirty-three thousand, four hundred twenty-one".