21003213 has 48 divisors (see below), whose sum is σ = 36771840. Its totient is φ = 10533600.

The previous prime is 21003179. The next prime is 21003223. The reversal of 21003213 is 31230012.

It is a happy number.

It is not a de Polignac number, because 21003213 - 2⁸ = 21002957 is a prime.

It is a super-2 number, since 2×21003213² = 882269912646738, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003223) 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 47 ways as a sum of consecutive naturals, for example, 49918 + ... + 50336.

It is an arithmetic number, because the mean of its divisors is an integer number (766080).

Almost surely, 2^21003213 is an apocalyptic number.

It is an amenable number.

21003213 is a deficient number, since it is larger than the sum of its proper divisors (15768627).

21003213 is a wasteful number, since it uses less digits than its factorization.

21003213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478 (or 471 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21003213 is about 4582.9262485883. The cubic root of 21003213 is about 275.9064874339.

Adding to 21003213 its reverse (31230012), we get a palindrome (52233225).

The spelling of 21003213 in words is "twenty-one million, three thousand, two hundred thirteen".