18968921 has 2 divisors, whose sum is σ = 18968922. Its totient is φ = 18968920.

The previous prime is 18968909. The next prime is 18968947. The reversal of 18968921 is 12986981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10471696 + 8497225 = 3236^2 + 2915^2 .

It is a cyclic number.

It is not a de Polignac number, because 18968921 - 2¹⁸ = 18706777 is a prime.

It is not a weakly prime, because it can be changed into another prime (18968021) 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, 9484460 + 9484461.

It is an arithmetic number, because the mean of its divisors is an integer number (9484461).

Almost surely, 2^18968921 is an apocalyptic number.

It is an amenable number.

18968921 is a deficient number, since it is larger than the sum of its proper divisors (1).

18968921 is an equidigital number, since it uses as much as digits as its factorization.

18968921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 44.

The square root of 18968921 is about 4355.3324786978. The cubic root of 18968921 is about 266.6945920408.

The spelling of 18968921 in words is "eighteen million, nine hundred sixty-eight thousand, nine hundred twenty-one".