20102191 has 4 divisors (see below), whose sum is σ = 20795400. Its totient is φ = 19408984.

The previous prime is 20102153. The next prime is 20102213. The reversal of 20102191 is 19120102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19120102 = 2 ⋅9560051.

It is a cyclic number.

It is not a de Polignac number, because 20102191 - 2¹⁹ = 19577903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20102111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 346561 + ... + 346618.

It is an arithmetic number, because the mean of its divisors is an integer number (5198850).

Almost surely, 2^20102191 is an apocalyptic number.

20102191 is a deficient number, since it is larger than the sum of its proper divisors (693209).

20102191 is an equidigital number, since it uses as much as digits as its factorization.

20102191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 693208.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 20102191 is about 4483.5466987643. The cubic root of 20102191 is about 271.9032915642.

Adding to 20102191 its reverse (19120102), we get a palindrome (39222293).

The spelling of 20102191 in words is "twenty million, one hundred two thousand, one hundred ninety-one".