218688426685656 has 192 divisors, whose sum is σ = 615315748320000. Its totient is φ = 72765886674816.

The previous prime is 218688426685649. The next prime is 218688426685679. The reversal of 218688426685656 is 656586624886812.

218688426685656 is a `hidden beast` number, since 2 + 1 + 8 + 6 + 8 + 8 + 42 + 6 + 6 + 8 + 565 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3432043765 + ... + 3432107483.

It is an arithmetic number, because the mean of its divisors is an integer number (3204769522500).

Almost surely, 2^{218688426685656} 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 218688426685656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (307657874160000).

218688426685656 is an abundant number, since it is smaller than the sum of its proper divisors (396627321634344).

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

218688426685656 is a wasteful number, since it uses less digits than its factorization.

218688426685656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66868 (or 66852 counting only the distinct ones).

The product of its digits is 12740198400, while the sum is 81.

The spelling of 218688426685656 in words is "two hundred eighteen trillion, six hundred eighty-eight billion, four hundred twenty-six million, six hundred eighty-five thousand, six hundred fifty-six".