20810191 has 2 divisors, whose sum is σ = 20810192. Its totient is φ = 20810190.

The previous prime is 20810189. The next prime is 20810203. The reversal of 20810191 is 19101802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20810191 - 2¹ = 20810189 is a prime.

Together with 20810189, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20814191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10405095 + 10405096.

It is an arithmetic number, because the mean of its divisors is an integer number (10405096).

Almost surely, 2^20810191 is an apocalyptic number.

20810191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20810191 is an equidigital number, since it uses as much as digits as its factorization.

20810191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 22.

The square root of 20810191 is about 4561.8188258632. The cubic root of 20810191 is about 275.0586805906.

Adding to 20810191 its reverse (19101802), we get a palindrome (39911993).

The spelling of 20810191 in words is "twenty million, eight hundred ten thousand, one hundred ninety-one".