1215765191 has 2 divisors, whose sum is σ = 1215765192. Its totient is φ = 1215765190.

The previous prime is 1215765167. The next prime is 1215765193. The reversal of 1215765191 is 1915675121.

It is a strong prime.

It is an emirp because it is prime and its reverse (1915675121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1215765191 - 2⁶ = 1215765127 is a prime.

Together with 1215765193, 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 (1215765193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607882595 + 607882596.

It is an arithmetic number, because the mean of its divisors is an integer number (607882596).

Almost surely, 2^1215765191 is an apocalyptic number.

1215765191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215765191 is an equidigital number, since it uses as much as digits as its factorization.

1215765191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18900, while the sum is 38.

The square root of 1215765191 is about 34867.8245808367. The cubic root of 1215765191 is about 1067.2919527939.

The spelling of 1215765191 in words is "one billion, two hundred fifteen million, seven hundred sixty-five thousand, one hundred ninety-one".