20211231191 has 2 divisors, whose sum is σ = 20211231192. Its totient is φ = 20211231190.

The previous prime is 20211231179. The next prime is 20211231197. The reversal of 20211231191 is 19113211202.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20211231191 - 2¹⁰ = 20211230167 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20211231197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10105615595 + 10105615596.

It is an arithmetic number, because the mean of its divisors is an integer number (10105615596).

Almost surely, 2^20211231191 is an apocalyptic number.

20211231191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20211231191 is an equidigital number, since it uses as much as digits as its factorization.

20211231191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 23.

Adding to 20211231191 its reverse (19113211202), we get a palindrome (39324442393).

The spelling of 20211231191 in words is "twenty billion, two hundred eleven million, two hundred thirty-one thousand, one hundred ninety-one".