21001221001213 has 2 divisors, whose sum is σ = 21001221001214. Its totient is φ = 21001221001212.

The previous prime is 21001221001207. The next prime is 21001221001219. The reversal of 21001221001213 is 31210012210012.

It is a balanced prime because it is at equal distance from previous prime (21001221001207) and next prime (21001221001219).

It can be written as a sum of positive squares in only one way, i.e., 11528109624249 + 9473111376964 = 3395307^2 + 3077842^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001221001213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001221001219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500610500606 + 10500610500607.

It is an arithmetic number, because the mean of its divisors is an integer number (10500610500607).

Almost surely, 2^{21001221001213} is an apocalyptic number.

It is an amenable number.

21001221001213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001221001213 is an equidigital number, since it uses as much as digits as its factorization.

21001221001213 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21001221001213 its reverse (31210012210012), we get a palindrome (52211233211225).

The spelling of 21001221001213 in words is "twenty-one trillion, one billion, two hundred twenty-one million, one thousand, two hundred thirteen".