18170021 has 4 divisors (see below), whose sum is σ = 18265344. Its totient is φ = 18074700.

The previous prime is 18169967. The next prime is 18170027. The reversal of 18170021 is 12007181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18170021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18169975 and 18170002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18170027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47375 + ... + 47756.

It is an arithmetic number, because the mean of its divisors is an integer number (4566336).

Almost surely, 2^18170021 is an apocalyptic number.

It is an amenable number.

18170021 is a deficient number, since it is larger than the sum of its proper divisors (95323).

18170021 is an equidigital number, since it uses as much as digits as its factorization.

18170021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95322.

The product of its (nonzero) digits is 112, while the sum is 20.

The square root of 18170021 is about 4262.6307604577. The cubic root of 18170021 is about 262.8967050875.

The spelling of 18170021 in words is "eighteen million, one hundred seventy thousand, twenty-one".