218909857 has 2 divisors, whose sum is σ = 218909858. Its totient is φ = 218909856.

The previous prime is 218909809. The next prime is 218909863. The reversal of 218909857 is 758909812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 215032896 + 3876961 = 14664^2 + 1969^2 .

It is a cyclic number.

It is not a de Polignac number, because 218909857 - 2⁷ = 218909729 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 218909857.

It is not a weakly prime, because it can be changed into another prime (218909897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109454928 + 109454929.

It is an arithmetic number, because the mean of its divisors is an integer number (109454929).

Almost surely, 2^218909857 is an apocalyptic number.

It is an amenable number.

218909857 is a deficient number, since it is larger than the sum of its proper divisors (1).

218909857 is an equidigital number, since it uses as much as digits as its factorization.

218909857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 362880, while the sum is 49.

The square root of 218909857 is about 14795.6026237528. The cubic root of 218909857 is about 602.6823029198.

The spelling of 218909857 in words is "two hundred eighteen million, nine hundred nine thousand, eight hundred fifty-seven".