1291547981 has 2 divisors, whose sum is σ = 1291547982. Its totient is φ = 1291547980.

The previous prime is 1291547951. The next prime is 1291547993. The reversal of 1291547981 is 1897451921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1288092100 + 3455881 = 35890^2 + 1859^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291547981 - 2¹⁰ = 1291546957 is a prime.

It is a super-2 number, since 2×1291547981² = 3336192374450352722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291547951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645773990 + 645773991.

It is an arithmetic number, because the mean of its divisors is an integer number (645773991).

Almost surely, 2^1291547981 is an apocalyptic number.

It is an amenable number.

1291547981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291547981 is an equidigital number, since it uses as much as digits as its factorization.

1291547981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 47.

The square root of 1291547981 is about 35938.1132086814. The cubic root of 1291547981 is about 1089.0224889482.

The spelling of 1291547981 in words is "one billion, two hundred ninety-one million, five hundred forty-seven thousand, nine hundred eighty-one".