218883661 has 2 divisors, whose sum is σ = 218883662. Its totient is φ = 218883660.

The previous prime is 218883659. The next prime is 218883673. The reversal of 218883661 is 166388812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216384100 + 2499561 = 14710^2 + 1581^2 .

It is a cyclic number.

It is not a de Polignac number, because 218883661 - 2¹ = 218883659 is a prime.

Together with 218883659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218887661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109441830 + 109441831.

It is an arithmetic number, because the mean of its divisors is an integer number (109441831).

Almost surely, 2^218883661 is an apocalyptic number.

It is an amenable number.

218883661 is a deficient number, since it is larger than the sum of its proper divisors (1).

218883661 is an equidigital number, since it uses as much as digits as its factorization.

218883661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 110592, while the sum is 43.

The square root of 218883661 is about 14794.7173342379. The cubic root of 218883661 is about 602.6582618288.

It can be divided in two parts, 2188 and 83661, that added together give a square (85849 = 293²).

The spelling of 218883661 in words is "two hundred eighteen million, eight hundred eighty-three thousand, six hundred sixty-one".