218384289064561 has 9 divisors (see below), whose sum is σ = 222583290129291. Its totient is φ = 214263062333112.

The previous prime is 218384289064531. The next prime is 218384289064607. The reversal of 218384289064561 is 165460982483812.

The square root of 218384289064561 is 14777831.

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

It can be written as a sum of positive squares in only one way, i.e., 157432604256225 + 60951684808336 = 12547215^2 + 7807156^2 .

It is not a de Polignac number, because 218384289064561 - 2¹³ = 218384289056369 is a prime.

It is a super-2 number, since 2×218384289064561² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218384289064531) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 783085630 + ... + 783364456.

Almost surely, 2^{218384289064561} is an apocalyptic number.

218384289064561 is the 14777831-st square number.

218384289064561 is the 7388916-th centered octagonal number.

It is an amenable number.

218384289064561 is a deficient number, since it is larger than the sum of its proper divisors (4199001064730).

218384289064561 is an frugal number, since it uses more digits than its factorization.

218384289064561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 557760 (or 278880 counting only the distinct ones).

The product of its (nonzero) digits is 159252480, while the sum is 67.

The spelling of 218384289064561 in words is "two hundred eighteen trillion, three hundred eighty-four billion, two hundred eighty-nine million, sixty-four thousand, five hundred sixty-one".