1271999 has 2 divisors, whose sum is σ = 1272000. Its totient is φ = 1271998.

The previous prime is 1271987. The next prime is 1272001. The reversal of 1271999 is 9991721.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1271999 - 2²⁰ = 223423 is a prime.

Together with 1272001, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1271929) 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, 635999 + 636000.

It is an arithmetic number, because the mean of its divisors is an integer number (636000).

2^1271999 is an apocalyptic number.

1271999 is a deficient number, since it is larger than the sum of its proper divisors (1).

1271999 is an equidigital number, since it uses as much as digits as its factorization.

1271999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10206, while the sum is 38.

The square root of 1271999 is about 1127.8293310603. The cubic root of 1271999 is about 108.3500019059.

The spelling of 1271999 in words is "one million, two hundred seventy-one thousand, nine hundred ninety-nine".