21210223 has 16 divisors (see below), whose sum is σ = 22857120. Its totient is φ = 19643904.

The previous prime is 21210221. The next prime is 21210227. The reversal of 21210223 is 32201212.

It is not a de Polignac number, because 21210223 - 2¹ = 21210221 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 (21210221) 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 15 ways as a sum of consecutive naturals, for example, 90915 + ... + 91147.

It is an arithmetic number, because the mean of its divisors is an integer number (1428570).

Almost surely, 2^21210223 is an apocalyptic number.

21210223 is a deficient number, since it is larger than the sum of its proper divisors (1646897).

21210223 is a wasteful number, since it uses less digits than its factorization.

21210223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 378.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21210223 is about 4605.4557863473. The cubic root of 21210223 is about 276.8099805881.

Adding to 21210223 its reverse (32201212), we get a palindrome (53411435).

The spelling of 21210223 in words is "twenty-one million, two hundred ten thousand, two hundred twenty-three".