218124021 has 4 divisors (see below), whose sum is σ = 290832032. Its totient is φ = 145416012.

The previous prime is 218124017. The next prime is 218124031. The reversal of 218124021 is 120421812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 218124021 - 2² = 218124017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218124001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36354001 + ... + 36354006.

It is an arithmetic number, because the mean of its divisors is an integer number (72708008).

Almost surely, 2^218124021 is an apocalyptic number.

It is an amenable number.

218124021 is a deficient number, since it is larger than the sum of its proper divisors (72708011).

218124021 is an equidigital number, since it uses as much as digits as its factorization.

218124021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72708010.

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 218124021 is about 14769.0223440822. The cubic root of 218124021 is about 601.9602746751.

Adding to 218124021 its reverse (120421812), we get a palindrome (338545833).

The spelling of 218124021 in words is "two hundred eighteen million, one hundred twenty-four thousand, twenty-one".