21211345517 has 2 divisors, whose sum is σ = 21211345518. Its totient is φ = 21211345516.

The previous prime is 21211345489. The next prime is 21211345567. The reversal of 21211345517 is 71554311212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20832303556 + 379041961 = 144334^2 + 19469^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211345517 - 2¹⁶ = 21211279981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211345567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605672758 + 10605672759.

It is an arithmetic number, because the mean of its divisors is an integer number (10605672759).

Almost surely, 2^21211345517 is an apocalyptic number.

It is an amenable number.

21211345517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211345517 is an equidigital number, since it uses as much as digits as its factorization.

21211345517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8400, while the sum is 32.

Adding to 21211345517 its reverse (71554311212), we get a palindrome (92765656729).

The spelling of 21211345517 in words is "twenty-one billion, two hundred eleven million, three hundred forty-five thousand, five hundred seventeen".