218873821 has 2 divisors, whose sum is σ = 218873822. Its totient is φ = 218873820.

The previous prime is 218873813. The next prime is 218873869. The reversal of 218873821 is 128378812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 204089796 + 14784025 = 14286^2 + 3845^2 .

It is a cyclic number.

It is not a de Polignac number, because 218873821 - 2³ = 218873813 is a prime.

It is a super-3 number, since 3×218873821³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218873801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109436910 + 109436911.

It is an arithmetic number, because the mean of its divisors is an integer number (109436911).

Almost surely, 2^218873821 is an apocalyptic number.

It is an amenable number.

218873821 is a deficient number, since it is larger than the sum of its proper divisors (1).

218873821 is an equidigital number, since it uses as much as digits as its factorization.

218873821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43008, while the sum is 40.

The square root of 218873821 is about 14794.3847793682. The cubic root of 218873821 is about 602.6492307813.

The spelling of 218873821 in words is "two hundred eighteen million, eight hundred seventy-three thousand, eight hundred twenty-one".