18690493 has 2 divisors, whose sum is σ = 18690494. Its totient is φ = 18690492.

The previous prime is 18690487. The next prime is 18690527. The reversal of 18690493 is 39409681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18645124 + 45369 = 4318^2 + 213^2 .

It is an emirp because it is prime and its reverse (39409681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18690493 - 2²¹ = 16593341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18694493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9345246 + 9345247.

It is an arithmetic number, because the mean of its divisors is an integer number (9345247).

Almost surely, 2^18690493 is an apocalyptic number.

It is an amenable number.

18690493 is a deficient number, since it is larger than the sum of its proper divisors (1).

18690493 is an equidigital number, since it uses as much as digits as its factorization.

18690493 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 18690493 is about 4323.2502819060. The cubic root of 18690493 is about 265.3832972344.

The spelling of 18690493 in words is "eighteen million, six hundred ninety thousand, four hundred ninety-three".