21122011217 has 2 divisors, whose sum is σ = 21122011218. Its totient is φ = 21122011216.

The previous prime is 21122011213. The next prime is 21122011243. The reversal of 21122011217 is 71211022112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20800562176 + 321449041 = 144224^2 + 17929^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122011217 - 2² = 21122011213 is a prime.

It is a super-2 number, since 2×21122011217² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21122011213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561005608 + 10561005609.

It is an arithmetic number, because the mean of its divisors is an integer number (10561005609).

Almost surely, 2^21122011217 is an apocalyptic number.

It is an amenable number.

21122011217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122011217 is an equidigital number, since it uses as much as digits as its factorization.

21122011217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112, while the sum is 20.

Adding to 21122011217 its reverse (71211022112), we get a palindrome (92333033329).

The spelling of 21122011217 in words is "twenty-one billion, one hundred twenty-two million, eleven thousand, two hundred seventeen".