21212003 has 4 divisors (see below), whose sum is σ = 22134288. Its totient is φ = 20289720.

The previous prime is 21211997. The next prime is 21212017. The reversal of 21212003 is 30021212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21212003 - 2¹⁰ = 21210979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212033) 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, 461108 + ... + 461153.

It is an arithmetic number, because the mean of its divisors is an integer number (5533572).

Almost surely, 2^21212003 is an apocalyptic number.

21212003 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21212003 is a deficient number, since it is larger than the sum of its proper divisors (922285).

21212003 is an equidigital number, since it uses as much as digits as its factorization.

21212003 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922284.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21212003 is about 4605.6490313527. The cubic root of 21212003 is about 276.8177238350.

Adding to 21212003 its reverse (30021212), we get a palindrome (51233215).

The spelling of 21212003 in words is "twenty-one million, two hundred twelve thousand, three".