18270021 has 32 divisors (see below), whose sum is σ = 30643200. Its totient is φ = 9406080.

The previous prime is 18270013. The next prime is 18270023. The reversal of 18270021 is 12007281.

It is not a de Polignac number, because 18270021 - 2³ = 18270013 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18270021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18270023) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 31825 + ... + 32393.

It is an arithmetic number, because the mean of its divisors is an integer number (957600).

Almost surely, 2^18270021 is an apocalyptic number.

18270021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18270021 is a deficient number, since it is larger than the sum of its proper divisors (12373179).

18270021 is a wasteful number, since it uses less digits than its factorization.

18270021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 18270021 is about 4274.3445111502. The cubic root of 18270021 is about 263.3781132343.

The spelling of 18270021 in words is "eighteen million, two hundred seventy thousand, twenty-one".