20109989 has 2 divisors, whose sum is σ = 20109990. Its totient is φ = 20109988.

The previous prime is 20109977. The next prime is 20110043. The reversal of 20109989 is 98990102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16240900 + 3869089 = 4030^2 + 1967^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20109989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20108989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10054994 + 10054995.

It is an arithmetic number, because the mean of its divisors is an integer number (10054995).

Almost surely, 2^20109989 is an apocalyptic number.

It is an amenable number.

20109989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20109989 is an equidigital number, since it uses as much as digits as its factorization.

20109989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 20109989 is about 4484.4162384863. The cubic root of 20109989 is about 271.9384457381.

The spelling of 20109989 in words is "twenty million, one hundred nine thousand, nine hundred eighty-nine".