2166781744512 has 768 divisors, whose sum is σ = 8382670732800. Its totient is φ = 520158412800.

The previous prime is 2166781744511. The next prime is 2166781744559. The reversal of 2166781744512 is 2154471876612.

It is a happy number.

2166781744512 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 7 + 81 + 7 + 44 + 512 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2166781744511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 69084738 + ... + 69116094.

It is an arithmetic number, because the mean of its divisors is an integer number (10914935850).

Almost surely, 2^{2166781744512} is an apocalyptic number.

2166781744512 is a gapful number since it is divisible by the number (22) 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 2166781744512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4191335366400).

2166781744512 is an abundant number, since it is smaller than the sum of its proper divisors (6215888988288).

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

2166781744512 is a wasteful number, since it uses less digits than its factorization.

2166781744512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31455 (or 31440 counting only the distinct ones).

The product of its digits is 4515840, while the sum is 54.

It can be divided in two parts, 216678 and 1744512, that added together give a triangular number (1961190 = T₁₉₈₀).

The spelling of 2166781744512 in words is "two trillion, one hundred sixty-six billion, seven hundred eighty-one million, seven hundred forty-four thousand, five hundred twelve".