18978893 has 2 divisors, whose sum is σ = 18978894. Its totient is φ = 18978892.

The previous prime is 18978871. The next prime is 18978901. The reversal of 18978893 is 39887981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18679684 + 299209 = 4322^2 + 547^2 .

It is a cyclic number.

It is not a de Polignac number, because 18978893 - 2⁸ = 18978637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18978803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9489446 + 9489447.

It is an arithmetic number, because the mean of its divisors is an integer number (9489447).

Almost surely, 2^18978893 is an apocalyptic number.

It is an amenable number.

18978893 is a deficient number, since it is larger than the sum of its proper divisors (1).

18978893 is an equidigital number, since it uses as much as digits as its factorization.

18978893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 53.

The square root of 18978893 is about 4356.4771318119. The cubic root of 18978893 is about 266.7413178154.

The spelling of 18978893 in words is "eighteen million, nine hundred seventy-eight thousand, eight hundred ninety-three".