18955021 has 2 divisors, whose sum is σ = 18955022. Its totient is φ = 18955020.

The previous prime is 18955019. The next prime is 18955033. The reversal of 18955021 is 12055981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18369796 + 585225 = 4286^2 + 765^2 .

It is a cyclic number.

It is not a de Polignac number, because 18955021 - 2¹ = 18955019 is a prime.

It is a super-2 number, since 2×18955021² = 718585642220882, which contains 22 as substring.

Together with 18955019, 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 (18955721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9477510 + 9477511.

It is an arithmetic number, because the mean of its divisors is an integer number (9477511).

Almost surely, 2^18955021 is an apocalyptic number.

It is an amenable number.

18955021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18955021 is an equidigital number, since it uses as much as digits as its factorization.

18955021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 31.

The square root of 18955021 is about 4353.7364412651. The cubic root of 18955021 is about 266.6294335169.

The spelling of 18955021 in words is "eighteen million, nine hundred fifty-five thousand, twenty-one".