1311661817856 has 680 divisors, whose sum is σ = 4289702173680. Its totient is φ = 396984582144.

The previous prime is 1311661817827. The next prime is 1311661817863. The reversal of 1311661817856 is 6587181661131.

1311661817856 is a `hidden beast` number, since 1 + 3 + 1 + 1 + 6 + 618 + 17 + 8 + 5 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

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 39 ways as a sum of consecutive naturals, for example, 5727780750 + ... + 5727780978.

Almost surely, 2^{1311661817856} is an apocalyptic number.

1311661817856 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 1311661817856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2144851086840).

1311661817856 is an abundant number, since it is smaller than the sum of its proper divisors (2978040355824).

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

1311661817856 is an frugal number, since it uses more digits than its factorization.

1311661817856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 369 (or 330 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 54.

The spelling of 1311661817856 in words is "one trillion, three hundred eleven billion, six hundred sixty-one million, eight hundred seventeen thousand, eight hundred fifty-six".