218313661 has 2 divisors, whose sum is σ = 218313662. Its totient is φ = 218313660.

The previous prime is 218313649. The next prime is 218313713. The reversal of 218313661 is 166313812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 186841561 + 31472100 = 13669^2 + 5610^2 .

It is a cyclic number.

It is not a de Polignac number, because 218313661 - 2¹⁷ = 218182589 is a prime.

It is equal to p_12034885 and since 218313661 and 12034885 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218313761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109156830 + 109156831.

It is an arithmetic number, because the mean of its divisors is an integer number (109156831).

Almost surely, 2^218313661 is an apocalyptic number.

It is an amenable number.

218313661 is a deficient number, since it is larger than the sum of its proper divisors (1).

218313661 is an equidigital number, since it uses as much as digits as its factorization.

218313661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 31.

The square root of 218313661 is about 14775.4411440065. The cubic root of 218313661 is about 602.1346749682.

The spelling of 218313661 in words is "two hundred eighteen million, three hundred thirteen thousand, six hundred sixty-one".