21121311017 has 2 divisors, whose sum is σ = 21121311018. Its totient is φ = 21121311016.

The previous prime is 21121311011. The next prime is 21121311047. The reversal of 21121311017 is 71011312112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21099305536 + 22005481 = 145256^2 + 4691^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121311017 - 2¹⁸ = 21121048873 is a prime.

It is a super-2 number, since 2×21121311017² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121311017.

It is not a weakly prime, because it can be changed into another prime (21121311011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560655508 + 10560655509.

It is an arithmetic number, because the mean of its divisors is an integer number (10560655509).

Almost surely, 2^21121311017 is an apocalyptic number.

It is an amenable number.

21121311017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121311017 is an equidigital number, since it uses as much as digits as its factorization.

21121311017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 20.

Adding to 21121311017 its reverse (71011312112), we get a palindrome (92132623129).

The spelling of 21121311017 in words is "twenty-one billion, one hundred twenty-one million, three hundred eleven thousand, seventeen".