1291583981 has 2 divisors, whose sum is σ = 1291583982. Its totient is φ = 1291583980.

The previous prime is 1291583939. The next prime is 1291584013. The reversal of 1291583981 is 1893851921.

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., 1031052100 + 260531881 = 32110^2 + 16141^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291583981 - 2¹⁴ = 1291567597 is a prime.

It is a super-2 number, since 2×1291583981² = 3336378359951616722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291883981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645791990 + 645791991.

It is an arithmetic number, because the mean of its divisors is an integer number (645791991).

Almost surely, 2^1291583981 is an apocalyptic number.

It is an amenable number.

1291583981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291583981 is an equidigital number, since it uses as much as digits as its factorization.

1291583981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 47.

The square root of 1291583981 is about 35938.6140662102. The cubic root of 1291583981 is about 1089.0326071541.

The spelling of 1291583981 in words is "one billion, two hundred ninety-one million, five hundred eighty-three thousand, nine hundred eighty-one".