18919493 has 2 divisors, whose sum is σ = 18919494. Its totient is φ = 18919492.

The previous prime is 18919451. The next prime is 18919499. The reversal of 18919493 is 39491981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17833729 + 1085764 = 4223^2 + 1042^2 .

It is a cyclic number.

It is not a de Polignac number, because 18919493 - 2⁸ = 18919237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18919499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459746 + 9459747.

It is an arithmetic number, because the mean of its divisors is an integer number (9459747).

Almost surely, 2^18919493 is an apocalyptic number.

It is an amenable number.

18919493 is a deficient number, since it is larger than the sum of its proper divisors (1).

18919493 is an equidigital number, since it uses as much as digits as its factorization.

18919493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 44.

The square root of 18919493 is about 4349.6543540838. The cubic root of 18919493 is about 266.4627453153.

The spelling of 18919493 in words is "eighteen million, nine hundred nineteen thousand, four hundred ninety-three".