18693889 has 2 divisors, whose sum is σ = 18693890. Its totient is φ = 18693888.

The previous prime is 18693881. The next prime is 18693901. The reversal of 18693889 is 98839681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10758400 + 7935489 = 3280^2 + 2817^2 .

It is an emirp because it is prime and its reverse (98839681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18693889 - 2³ = 18693881 is a prime.

It is a super-2 number, since 2×18693889² = 698922971888642, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18693881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9346944 + 9346945.

It is an arithmetic number, because the mean of its divisors is an integer number (9346945).

Almost surely, 2^18693889 is an apocalyptic number.

It is an amenable number.

18693889 is a deficient number, since it is larger than the sum of its proper divisors (1).

18693889 is an equidigital number, since it uses as much as digits as its factorization.

18693889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 746496, while the sum is 52.

The square root of 18693889 is about 4323.6430241175. The cubic root of 18693889 is about 265.3993693465.

The spelling of 18693889 in words is "eighteen million, six hundred ninety-three thousand, eight hundred eighty-nine".