21012000011221 has 2 divisors, whose sum is σ = 21012000011222. Its totient is φ = 21012000011220.

The previous prime is 21012000011207. The next prime is 21012000011243. The reversal of 21012000011221 is 12211000021012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20470973564196 + 541026447025 = 4524486^2 + 735545^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012000011221 - 2¹¹ = 21012000009173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012000011251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506000005610 + 10506000005611.

It is an arithmetic number, because the mean of its divisors is an integer number (10506000005611).

Almost surely, 2^{21012000011221} is an apocalyptic number.

It is an amenable number.

21012000011221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012000011221 is an equidigital number, since it uses as much as digits as its factorization.

21012000011221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21012000011221 its reverse (12211000021012), we get a palindrome (33223000032233).

The spelling of 21012000011221 in words is "twenty-one trillion, twelve billion, eleven thousand, two hundred twenty-one".