21003121213 has 2 divisors, whose sum is σ = 21003121214. Its totient is φ = 21003121212.

The previous prime is 21003121169. The next prime is 21003121241. The reversal of 21003121213 is 31212130012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15208562329 + 5794558884 = 123323^2 + 76122^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21003121213 is a prime.

It is a super-2 number, since 2×21003121213² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21003121273) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501560606 + 10501560607.

It is an arithmetic number, because the mean of its divisors is an integer number (10501560607).

Almost surely, 2^21003121213 is an apocalyptic number.

It is an amenable number.

21003121213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003121213 is an equidigital number, since it uses as much as digits as its factorization.

21003121213 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21003121213 its reverse (31212130012), we get a palindrome (52215251225).

The spelling of 21003121213 in words is "twenty-one billion, three million, one hundred twenty-one thousand, two hundred thirteen".