1251279191 has 2 divisors, whose sum is σ = 1251279192. Its totient is φ = 1251279190.

The previous prime is 1251279151. The next prime is 1251279193. The reversal of 1251279191 is 1919721521.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1251279191 - 2²⁶ = 1184170327 is a prime.

It is a super-2 number, since 2×1251279191² = 3131399227659228962, which contains 22 as substring.

Together with 1251279193, 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 (1251279193) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 625639595 + 625639596.

It is an arithmetic number, because the mean of its divisors is an integer number (625639596).

Almost surely, 2^1251279191 is an apocalyptic number.

1251279191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1251279191 is an equidigital number, since it uses as much as digits as its factorization.

1251279191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11340, while the sum is 38.

The square root of 1251279191 is about 35373.4249260656. The cubic root of 1251279191 is about 1077.5846775362.

The spelling of 1251279191 in words is "one billion, two hundred fifty-one million, two hundred seventy-nine thousand, one hundred ninety-one".