18943121 has 2 divisors, whose sum is σ = 18943122. Its totient is φ = 18943120.

The previous prime is 18943103. The next prime is 18943129. The reversal of 18943121 is 12134981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18395521 + 547600 = 4289^2 + 740^2 .

It is a cyclic number.

It is not a de Polignac number, because 18943121 - 2²² = 14748817 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18943129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9471560 + 9471561.

It is an arithmetic number, because the mean of its divisors is an integer number (9471561).

Almost surely, 2^18943121 is an apocalyptic number.

It is an amenable number.

18943121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18943121 is an equidigital number, since it uses as much as digits as its factorization.

18943121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 29.

The square root of 18943121 is about 4352.3695844907. The cubic root of 18943121 is about 266.5736250062.

The spelling of 18943121 in words is "eighteen million, nine hundred forty-three thousand, one hundred twenty-one".