218408968739556 has 189 divisors, whose sum is σ = 666639486804249. Its totient is φ = 62400966401088.

The previous prime is 218408968739539. The next prime is 218408968739581. The reversal of 218408968739556 is 655937869804812.

The square root of 218408968739556 is 14778666.

It is a perfect power (a square), and thus also a powerful number.

218408968739556 is a `hidden beast` number, since 2 + 1 + 8 + 40 + 89 + 68 + 7 + 395 + 56 = 666.

It can be written as a sum of positive squares in only one way, i.e., 89195369148900 + 129213599590656 = 9444330^2 + 11367216^2 .

It is a tau number, because it is divible by the number of its divisors (189).

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

It is an unprimeable number.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 5586316200 + ... + 5586355296.

It is a 1-persistent number, because it is pandigital, but 2⋅218408968739556 = 436817937479112 is not.

Almost surely, 2^{218408968739556} is an apocalyptic number.

218408968739556 is the 14778666-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 218408968739556

218408968739556 is an abundant number, since it is smaller than the sum of its proper divisors (448230518064693).

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

218408968739556 is an frugal number, since it uses more digits than its factorization.

218408968739556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78230 (or 39109 counting only the distinct ones).

The product of its (nonzero) digits is 6270566400, while the sum is 81.

218408968739556 divided by its sum of digits (81) gives a square (2696407021476 = 1642074²).

The spelling of 218408968739556 in words is "two hundred eighteen trillion, four hundred eight billion, nine hundred sixty-eight million, seven hundred thirty-nine thousand, five hundred fifty-six".