21217223 has 2 divisors, whose sum is σ = 21217224. Its totient is φ = 21217222.

The previous prime is 21217199. The next prime is 21217249. The reversal of 21217223 is 32271212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21217223 - 2⁶ = 21217159 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21217195 and 21217204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21207223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608611 + 10608612.

It is an arithmetic number, because the mean of its divisors is an integer number (10608612).

Almost surely, 2^21217223 is an apocalyptic number.

21217223 is a deficient number, since it is larger than the sum of its proper divisors (1).

21217223 is an equidigital number, since it uses as much as digits as its factorization.

21217223 is an evil number, because the sum of its binary digits is even.

The product of its digits is 336, while the sum is 20.

The square root of 21217223 is about 4606.2156918668. The cubic root of 21217223 is about 276.8404290616.

Adding to 21217223 its reverse (32271212), we get a palindrome (53488435).

The spelling of 21217223 in words is "twenty-one million, two hundred seventeen thousand, two hundred twenty-three".