18836021 has 4 divisors (see below), whose sum is σ = 19274112. Its totient is φ = 18397932.

The previous prime is 18836009. The next prime is 18836033. The reversal of 18836021 is 12063881.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12063881 = 41 ⋅294241.

It is an interprime number because it is at equal distance from previous prime (18836009) and next prime (18836033).

It is a cyclic number.

It is not a de Polignac number, because 18836021 - 2²² = 14641717 is a prime.

It is a super-2 number, since 2×18836021² = 709591374224882, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18836821) 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, 218981 + ... + 219066.

It is an arithmetic number, because the mean of its divisors is an integer number (4818528).

Almost surely, 2^18836021 is an apocalyptic number.

It is an amenable number.

18836021 is a deficient number, since it is larger than the sum of its proper divisors (438091).

18836021 is an equidigital number, since it uses as much as digits as its factorization.

18836021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 438090.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 18836021 is about 4340.0485020331. The cubic root of 18836021 is about 266.0702934809.

The spelling of 18836021 in words is "eighteen million, eight hundred thirty-six thousand, twenty-one".