218211421 has 4 divisors (see below), whose sum is σ = 218718144. Its totient is φ = 217704700.

The previous prime is 218211407. The next prime is 218211431. The reversal of 218211421 is 124112812.

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 a cyclic number.

It is not a de Polignac number, because 218211421 - 2⁷ = 218211293 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 218211392 and 218211401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218211431) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 252715 + ... + 253576.

It is an arithmetic number, because the mean of its divisors is an integer number (54679536).

Almost surely, 2^218211421 is an apocalyptic number.

It is an amenable number.

218211421 is a deficient number, since it is larger than the sum of its proper divisors (506723).

218211421 is an equidigital number, since it uses as much as digits as its factorization.

218211421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 506722.

The product of its digits is 256, while the sum is 22.

The square root of 218211421 is about 14771.9809436649. The cubic root of 218211421 is about 602.0406636550.

The spelling of 218211421 in words is "two hundred eighteen million, two hundred eleven thousand, four hundred twenty-one".