21187786761191 has 2 divisors, whose sum is σ = 21187786761192. Its totient is φ = 21187786761190.

The previous prime is 21187786761187. The next prime is 21187786761263. The reversal of 21187786761191 is 19116768778112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21187786761191 - 2² = 21187786761187 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21187786761151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10593893380595 + 10593893380596.

It is an arithmetic number, because the mean of its divisors is an integer number (10593893380596).

Almost surely, 2^{21187786761191} is an apocalyptic number.

21187786761191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21187786761191 is an equidigital number, since it uses as much as digits as its factorization.

21187786761191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14224896, while the sum is 65.

The spelling of 21187786761191 in words is "twenty-one trillion, one hundred eighty-seven billion, seven hundred eighty-six million, seven hundred sixty-one thousand, one hundred ninety-one".