18935921 has 2 divisors, whose sum is σ = 18935922. Its totient is φ = 18935920.

The previous prime is 18935911. The next prime is 18935929. The reversal of 18935921 is 12953981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11971600 + 6964321 = 3460^2 + 2639^2 .

It is a cyclic number.

It is not a de Polignac number, because 18935921 - 2¹⁰ = 18934897 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 (18935929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9467960 + 9467961.

It is an arithmetic number, because the mean of its divisors is an integer number (9467961).

Almost surely, 2^18935921 is an apocalyptic number.

It is an amenable number.

18935921 is a deficient number, since it is larger than the sum of its proper divisors (1).

18935921 is an equidigital number, since it uses as much as digits as its factorization.

18935921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 38.

The square root of 18935921 is about 4351.5423702407. The cubic root of 18935921 is about 266.5398471629.

The spelling of 18935921 in words is "eighteen million, nine hundred thirty-five thousand, nine hundred twenty-one".