218876921 has 4 divisors (see below), whose sum is σ = 231752052. Its totient is φ = 206001792.

The previous prime is 218876897. The next prime is 218876927. The reversal of 218876921 is 129678812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 204919225 + 13957696 = 14315^2 + 3736^2 .

It is a cyclic number.

It is not a de Polignac number, because 218876921 - 2¹⁸ = 218614777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218876927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6437540 + ... + 6437573.

It is an arithmetic number, because the mean of its divisors is an integer number (57938013).

Almost surely, 2^218876921 is an apocalyptic number.

It is an amenable number.

218876921 is a deficient number, since it is larger than the sum of its proper divisors (12875131).

218876921 is a wasteful number, since it uses less digits than its factorization.

218876921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12875130.

The product of its digits is 96768, while the sum is 44.

The square root of 218876921 is about 14794.4895484772. The cubic root of 218876921 is about 602.6520759576.

The spelling of 218876921 in words is "two hundred eighteen million, eight hundred seventy-six thousand, nine hundred twenty-one".