218257861 has 2 divisors, whose sum is σ = 218257862. Its totient is φ = 218257860.

The previous prime is 218257843. The next prime is 218257889. The reversal of 218257861 is 168752812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 215796100 + 2461761 = 14690^2 + 1569^2 .

It is a cyclic number.

It is not a de Polignac number, because 218257861 - 2¹¹ = 218255813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218257261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109128930 + 109128931.

It is an arithmetic number, because the mean of its divisors is an integer number (109128931).

Almost surely, 2^218257861 is an apocalyptic number.

It is an amenable number.

218257861 is a deficient number, since it is larger than the sum of its proper divisors (1).

218257861 is an equidigital number, since it uses as much as digits as its factorization.

218257861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 53760, while the sum is 40.

The square root of 218257861 is about 14773.5527548386. The cubic root of 218257861 is about 602.0833696159.

The spelling of 218257861 in words is "two hundred eighteen million, two hundred fifty-seven thousand, eight hundred sixty-one".