1291912681 has 2 divisors, whose sum is σ = 1291912682. Its totient is φ = 1291912680.

The previous prime is 1291912669. The next prime is 1291912709. The reversal of 1291912681 is 1862191921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 958521600 + 333391081 = 30960^2 + 18259^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291912681 - 2⁵ = 1291912649 is a prime.

It is a super-2 number, since 2×1291912681² = 3338076750657215522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1291912621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645956340 + 645956341.

It is an arithmetic number, because the mean of its divisors is an integer number (645956341).

Almost surely, 2^1291912681 is an apocalyptic number.

It is an amenable number.

1291912681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291912681 is an equidigital number, since it uses as much as digits as its factorization.

1291912681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 40.

The square root of 1291912681 is about 35943.1868509179. The cubic root of 1291912681 is about 1089.1249833013.

It can be divided in two parts, 12919 and 12681, that added together give a square (25600 = 160²).

The spelling of 1291912681 in words is "one billion, two hundred ninety-one million, nine hundred twelve thousand, six hundred eighty-one".