20109191 has 2 divisors, whose sum is σ = 20109192. Its totient is φ = 20109190.

The previous prime is 20109161. The next prime is 20109197. The reversal of 20109191 is 19190102.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20109191 - 2¹⁰ = 20108167 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20109197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10054595 + 10054596.

It is an arithmetic number, because the mean of its divisors is an integer number (10054596).

Almost surely, 2^20109191 is an apocalyptic number.

20109191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20109191 is an equidigital number, since it uses as much as digits as its factorization.

20109191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 23.

The square root of 20109191 is about 4484.3272628121. The cubic root of 20109191 is about 271.9348486907.

Adding to 20109191 its reverse (19190102), we get a palindrome (39299293).

It can be divided in two parts, 201091 and 91, that multiplied together give a palindrome (18299281).

The spelling of 20109191 in words is "twenty million, one hundred nine thousand, one hundred ninety-one".