21012021021217 has 2 divisors, whose sum is σ = 21012021021218. Its totient is φ = 21012021021216.

The previous prime is 21012021021193. The next prime is 21012021021241. The reversal of 21012021021217 is 71212012021012.

It is a balanced prime because it is at equal distance from previous prime (21012021021193) and next prime (21012021021241).

It can be written as a sum of positive squares in only one way, i.e., 12202753643536 + 8809267377681 = 3493244^2 + 2968041^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012021021217 - 2³⁵ = 20977661282849 is a prime.

It is a super-2 number, since 2×21012021021217² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21012021421217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506010510608 + 10506010510609.

It is an arithmetic number, because the mean of its divisors is an integer number (10506010510609).

Almost surely, 2^{21012021021217} is an apocalyptic number.

It is an amenable number.

21012021021217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012021021217 is an equidigital number, since it uses as much as digits as its factorization.

21012021021217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 224, while the sum is 22.

Adding to 21012021021217 its reverse (71212012021012), we get a palindrome (92224033042229).

The spelling of 21012021021217 in words is "twenty-one trillion, twelve billion, twenty-one million, twenty-one thousand, two hundred seventeen".