21123003213 has 24 divisors (see below), whose sum is σ = 32862998168. Its totient is φ = 12996796032.

The previous prime is 21123003199. The next prime is 21123003227. The reversal of 21123003213 is 31230032112.

It is an interprime number because it is at equal distance from previous prime (21123003199) and next prime (21123003227).

It can be written as a sum of positive squares in 4 ways, for example, as 635947524 + 20487055689 = 25218^2 + 143133^2 .

It is not a de Polignac number, because 21123003213 - 2¹⁰ = 21123002189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123003283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1273731 + ... + 1290207.

Almost surely, 2^21123003213 is an apocalyptic number.

It is an amenable number.

21123003213 is a deficient number, since it is larger than the sum of its proper divisors (11739994955).

21123003213 is a wasteful number, since it uses less digits than its factorization.

21123003213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27453 (or 27450 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

Adding to 21123003213 its reverse (31230032112), we get a palindrome (52353035325).

It can be divided in two parts, 21123003 and 213, that added together give a square (21123216 = 4596²).

The spelling of 21123003213 in words is "twenty-one billion, one hundred twenty-three million, three thousand, two hundred thirteen".