18689989 has 2 divisors, whose sum is σ = 18689990. Its totient is φ = 18689988.

The previous prime is 18689963. The next prime is 18690019. The reversal of 18689989 is 98998681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15539364 + 3150625 = 3942^2 + 1775^2 .

It is a cyclic number.

It is not a de Polignac number, because 18689989 - 2¹³ = 18681797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18689959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9344994 + 9344995.

It is an arithmetic number, because the mean of its divisors is an integer number (9344995).

Almost surely, 2^18689989 is an apocalyptic number.

It is an amenable number.

18689989 is a deficient number, since it is larger than the sum of its proper divisors (1).

18689989 is an equidigital number, since it uses as much as digits as its factorization.

18689989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2239488, while the sum is 58.

The square root of 18689989 is about 4323.1919920355. The cubic root of 18689989 is about 265.3809118080.

The spelling of 18689989 in words is "eighteen million, six hundred eighty-nine thousand, nine hundred eighty-nine".