21218226 has 8 divisors (see below), whose sum is σ = 42436464. Its totient is φ = 7072740.

The previous prime is 21218191. The next prime is 21218233. The reversal of 21218226 is 62281212.

It is a sphenic number, since it is the product of 3 distinct primes.

21218226 is an admirable number.

It is a super-2 number, since 2×21218226² = 900426229174152, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21218196 and 21218205.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1768180 + ... + 1768191.

It is an arithmetic number, because the mean of its divisors is an integer number (5304558).

Almost surely, 2^21218226 is an apocalyptic number.

21218226 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21218226 is a wasteful number, since it uses less digits than its factorization.

21218226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3536376.

The product of its digits is 768, while the sum is 24.

The square root of 21218226 is about 4606.3245652038. The cubic root of 21218226 is about 276.8447913443.

Adding to 21218226 its reverse (62281212), we get a palindrome (83499438).

The spelling of 21218226 in words is "twenty-one million, two hundred eighteen thousand, two hundred twenty-six".