20870191 has 2 divisors, whose sum is σ = 20870192. Its totient is φ = 20870190.

The previous prime is 20870159. The next prime is 20870219. The reversal of 20870191 is 19107802.

It is an a-pointer prime, because the next prime (20870219) can be obtained adding 20870191 to its sum of digits (28).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20870191 - 2⁵ = 20870159 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 (20870791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10435095 + 10435096.

It is an arithmetic number, because the mean of its divisors is an integer number (10435096).

Almost surely, 2^20870191 is an apocalyptic number.

20870191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20870191 is an equidigital number, since it uses as much as digits as its factorization.

20870191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 20870191 is about 4568.3904167661. The cubic root of 20870191 is about 275.3227769203.

Adding to 20870191 its reverse (19107802), we get a palindrome (39977993).

The spelling of 20870191 in words is "twenty million, eight hundred seventy thousand, one hundred ninety-one".