20121191 has 2 divisors, whose sum is σ = 20121192. Its totient is φ = 20121190.

The previous prime is 20121173. The next prime is 20121193. The reversal of 20121191 is 19112102.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20121191 is a prime.

Together with 20121193, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20121193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10060595 + 10060596.

It is an arithmetic number, because the mean of its divisors is an integer number (10060596).

Almost surely, 2^20121191 is an apocalyptic number.

20121191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20121191 is an equidigital number, since it uses as much as digits as its factorization.

20121191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 17.

The square root of 20121191 is about 4485.6650565997. The cubic root of 20121191 is about 271.9889295884.

Adding to 20121191 its reverse (19112102), we get a palindrome (39233293).

The spelling of 20121191 in words is "twenty million, one hundred twenty-one thousand, one hundred ninety-one".