1291316921 has 2 divisors, whose sum is σ = 1291316922. Its totient is φ = 1291316920.

The previous prime is 1291316863. The next prime is 1291316933. The reversal of 1291316921 is 1296131921.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 944947600 + 346369321 = 30740^2 + 18611^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291316921 - 2¹⁰ = 1291315897 is a prime.

It is not a weakly prime, because it can be changed into another prime (1291316941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645658460 + 645658461.

It is an arithmetic number, because the mean of its divisors is an integer number (645658461).

Almost surely, 2^1291316921 is an apocalyptic number.

It is an amenable number.

1291316921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291316921 is an equidigital number, since it uses as much as digits as its factorization.

1291316921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5832, while the sum is 35.

The square root of 1291316921 is about 35934.8983719170. The cubic root of 1291316921 is about 1088.9575424532.

The spelling of 1291316921 in words is "one billion, two hundred ninety-one million, three hundred sixteen thousand, nine hundred twenty-one".