1291920681 has 32 divisors (see below), whose sum is σ = 1833701760. Its totient is φ = 807657984.

The previous prime is 1291920677. The next prime is 1291920683. The reversal of 1291920681 is 1860291921.

It is not a de Polignac number, because 1291920681 - 2² = 1291920677 is a prime.

It is a super-2 number, since 2×1291920681² = 3338118091991007522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1291920683) 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 in 31 ways as a sum of consecutive naturals, for example, 736101 + ... + 737853.

It is an arithmetic number, because the mean of its divisors is an integer number (57303180).

Almost surely, 2^1291920681 is an apocalyptic number.

It is an amenable number.

1291920681 is a deficient number, since it is larger than the sum of its proper divisors (541781079).

1291920681 is a wasteful number, since it uses less digits than its factorization.

1291920681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2025.

The product of its (nonzero) digits is 15552, while the sum is 39.

The square root of 1291920681 is about 35943.2981374832. The cubic root of 1291920681 is about 1089.1272313845.

The spelling of 1291920681 in words is "one billion, two hundred ninety-one million, nine hundred twenty thousand, six hundred eighty-one".