1291321681 has 16 divisors (see below), whose sum is σ = 1466920000. Its totient is φ = 1126882368.

The previous prime is 1291321679. The next prime is 1291321687. The reversal of 1291321681 is 1861231921.

It is a cyclic number.

It is not a de Polignac number, because 1291321681 - 2¹ = 1291321679 is a prime.

It is a super-2 number, since 2×1291321681² = 3335023367641331522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1291321687) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 118015 + ... + 128491.

It is an arithmetic number, because the mean of its divisors is an integer number (91682500).

Almost surely, 2^1291321681 is an apocalyptic number.

It is an amenable number.

1291321681 is a deficient number, since it is larger than the sum of its proper divisors (175598319).

1291321681 is a wasteful number, since it uses less digits than its factorization.

1291321681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11008.

The product of its digits is 5184, while the sum is 34.

The square root of 1291321681 is about 35934.9646027375. The cubic root of 1291321681 is about 1088.9588804752.

The spelling of 1291321681 in words is "one billion, two hundred ninety-one million, three hundred twenty-one thousand, six hundred eighty-one".