18358021 has 4 divisors (see below), whose sum is σ = 20026944. Its totient is φ = 16689100.

The previous prime is 18358003. The next prime is 18358049. The reversal of 18358021 is 12085381.

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 not a de Polignac number, because 18358021 - 2⁹ = 18357509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18358001) 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, 834445 + ... + 834466.

It is an arithmetic number, because the mean of its divisors is an integer number (5006736).

Almost surely, 2^18358021 is an apocalyptic number.

18358021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18358021 is a deficient number, since it is larger than the sum of its proper divisors (1668923).

18358021 is a wasteful number, since it uses less digits than its factorization.

18358021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1668922.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 18358021 is about 4284.6261213786. The cubic root of 18358021 is about 263.8003014204.

The spelling of 18358021 in words is "eighteen million, three hundred fifty-eight thousand, twenty-one".