18841021 has 2 divisors, whose sum is σ = 18841022. Its totient is φ = 18841020.

The previous prime is 18841019. The next prime is 18841061. The reversal of 18841021 is 12014881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18404100 + 436921 = 4290^2 + 661^2 .

It is an emirp because it is prime and its reverse (12014881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18841021 - 2¹ = 18841019 is a prime.

Together with 18841019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18841061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9420510 + 9420511.

It is an arithmetic number, because the mean of its divisors is an integer number (9420511).

Almost surely, 2^18841021 is an apocalyptic number.

It is an amenable number.

18841021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18841021 is an equidigital number, since it uses as much as digits as its factorization.

18841021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 512, while the sum is 25.

The square root of 18841021 is about 4340.6244942404. The cubic root of 18841021 is about 266.0938340820.

It can be divided in two parts, 188 and 41021, that added together give a square (41209 = 203²).

The spelling of 18841021 in words is "eighteen million, eight hundred forty-one thousand, twenty-one".