18220789 has 2 divisors, whose sum is σ = 18220790. Its totient is φ = 18220788.

The previous prime is 18220781. The next prime is 18220799. The reversal of 18220789 is 98702281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17918289 + 302500 = 4233^2 + 550^2 .

It is an emirp because it is prime and its reverse (98702281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18220789 - 2³ = 18220781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18220781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9110394 + 9110395.

It is an arithmetic number, because the mean of its divisors is an integer number (9110395).

Almost surely, 2^18220789 is an apocalyptic number.

It is an amenable number.

18220789 is a deficient number, since it is larger than the sum of its proper divisors (1).

18220789 is an equidigital number, since it uses as much as digits as its factorization.

18220789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 18220789 is about 4268.5816145413. The cubic root of 18220789 is about 263.1413265015.

The spelling of 18220789 in words is "eighteen million, two hundred twenty thousand, seven hundred eighty-nine".