21312012213 has 18 divisors (see below), whose sum is σ = 31516598646. Its totient is φ = 13877578512.

The previous prime is 21312012203. The next prime is 21312012269. The reversal of 21312012213 is 31221021312.

It can be written as a sum of positive squares in only one way, i.e., 20025929169 + 1286083044 = 141513^2 + 35862^2 .

It is not a de Polignac number, because 21312012213 - 2⁵ = 21312012181 is a prime.

It is a super-2 number, since 2×21312012213² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312012203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 623706 + ... + 656987.

It is an arithmetic number, because the mean of its divisors is an integer number (1750922147).

Almost surely, 2^21312012213 is an apocalyptic number.

It is an amenable number.

21312012213 is a deficient number, since it is larger than the sum of its proper divisors (10204586433).

21312012213 is a wasteful number, since it uses less digits than its factorization.

21312012213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280785 (or 1280739 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21312012213 its reverse (31221021312), we get a palindrome (52533033525).

Subtracting 21312012213 from its reverse (31221021312), we obtain a palindrome (9909009099).

The spelling of 21312012213 in words is "twenty-one billion, three hundred twelve million, twelve thousand, two hundred thirteen".