1291999 has 2 divisors, whose sum is σ = 1292000.
Its totient is φ = 1291998.
The previous prime is 1291991. The next prime is 1292009. The reversal of 1291999 is 9991921.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 1291999 - 23 = 1291991 is a prime.
It is a super-2 number, since 2×12919992 = 3338522832002, which contains 22 as substring.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (1291991) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645999 + 646000.
It is an arithmetic number, because the mean of its divisors is an integer number (646000).
21291999 is an apocalyptic number.
1291999 is a deficient number, since it is larger than the sum of its proper divisors (1).
1291999 is an equidigital number, since it uses as much as digits as its factorization.
1291999 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 13122, while the sum is 40.
The square root of 1291999 is about 1136.6613391860.
The cubic root of 1291999 is about 108.9149239349.
The spelling of 1291999 in words is "one million, two hundred ninety-one thousand, nine hundred ninety-nine".