1291784256 has 252 divisors, whose sum is σ = 4427169708. Its totient is φ = 358815744.

The previous prime is 1291784239. The next prime is 1291784261. The reversal of 1291784256 is 6524871921.

It can be written as a sum of positive squares in 2 ways, for example, as 1073217600 + 218566656 = 32760^2 + 14784^2 .

It is a tau number, because it is divible by the number of its divisors (252).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1043670 + ... + 1044906.

Almost surely, 2^1291784256 is an apocalyptic number.

1291784256 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1291784256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2213584854).

1291784256 is an abundant number, since it is smaller than the sum of its proper divisors (3135385452).

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

1291784256 is a wasteful number, since it uses less digits than its factorization.

1291784256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1306 (or 1286 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The square root of 1291784256 is about 35941.4003066102. The cubic root of 1291784256 is about 1089.0888932690.

The spelling of 1291784256 in words is "one billion, two hundred ninety-one million, seven hundred eighty-four thousand, two hundred fifty-six".