18122021 has 2 divisors, whose sum is σ = 18122022. Its totient is φ = 18122020.

The previous prime is 18121997. The next prime is 18122023. The reversal of 18122021 is 12022181.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13653025 + 4468996 = 3695^2 + 2114^2 .

It is an emirp because it is prime and its reverse (12022181) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18122021 is a prime.

Together with 18122023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18122023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9061010 + 9061011.

It is an arithmetic number, because the mean of its divisors is an integer number (9061011).

Almost surely, 2^18122021 is an apocalyptic number.

It is an amenable number.

18122021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18122021 is an equidigital number, since it uses as much as digits as its factorization.

18122021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 18122021 is about 4256.9967112978. The cubic root of 18122021 is about 262.6650016285.

The spelling of 18122021 in words is "eighteen million, one hundred twenty-two thousand, twenty-one".