1291661984 has 48 divisors (see below), whose sum is σ = 2615457600. Its totient is φ = 627669504.

The previous prime is 1291661977. The next prime is 1291662011. The reversal of 1291661984 is 4891661921.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164189 + ... + 171875.

It is an arithmetic number, because the mean of its divisors is an integer number (54488700).

Almost surely, 2^1291661984 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1291661984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1307728800).

1291661984 is an abundant number, since it is smaller than the sum of its proper divisors (1323795616).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1291661984 is an equidigital number, since it uses as much as digits as its factorization.

1291661984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7845 (or 7837 counting only the distinct ones).

The product of its digits is 186624, while the sum is 47.

The square root of 1291661984 is about 35939.6992753139. The cubic root of 1291661984 is about 1089.0545301318.

The spelling of 1291661984 in words is "one billion, two hundred ninety-one million, six hundred sixty-one thousand, nine hundred eighty-four".