1291909 has 2 divisors, whose sum is σ = 1291910. Its totient is φ = 1291908.

The previous prime is 1291907. The next prime is 1291931. The reversal of 1291909 is 9091921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 675684 + 616225 = 822^2 + 785^2 .

It is an emirp because it is prime and its reverse (9091921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1291909 - 2¹ = 1291907 is a prime.

Together with 1291907, it forms a pair of twin primes.

1291909 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645954 + 645955.

It is an arithmetic number, because the mean of its divisors is an integer number (645955).

2^1291909 is an apocalyptic number.

It is an amenable number.

1291909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291909 is an equidigital number, since it uses as much as digits as its factorization.

1291909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 31.

The square root of 1291909 is about 1136.6217488681. The cubic root of 1291909 is about 108.9123948899.

The spelling of 1291909 in words is "one million, two hundred ninety-one thousand, nine hundred nine".