20618489 has 2 divisors, whose sum is σ = 20618490. Its totient is φ = 20618488.

The previous prime is 20618459. The next prime is 20618491. The reversal of 20618489 is 98481602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20611600 + 6889 = 4540^2 + 83^2 .

It is a cyclic number.

It is not a de Polignac number, because 20618489 - 2⁸ = 20618233 is a prime.

Together with 20618491, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20618459) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10309244 + 10309245.

It is an arithmetic number, because the mean of its divisors is an integer number (10309245).

Almost surely, 2^20618489 is an apocalyptic number.

It is an amenable number.

20618489 is a deficient number, since it is larger than the sum of its proper divisors (1).

20618489 is an equidigital number, since it uses as much as digits as its factorization.

20618489 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 20618489 is about 4540.7586370561. The cubic root of 20618489 is about 274.2114667457.

The spelling of 20618489 in words is "twenty million, six hundred eighteen thousand, four hundred eighty-nine".