21102111120521 has 2 divisors, whose sum is σ = 21102111120522. Its totient is φ = 21102111120520.

The previous prime is 21102111120509. The next prime is 21102111120539. The reversal of 21102111120521 is 12502111120112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13791382005625 + 7310729114896 = 3713675^2 + 2703836^2 .

It is a cyclic number.

It is not a de Polignac number, because 21102111120521 - 2⁴² = 16704064609417 is a prime.

It is a super-2 number, since 2×21102111120521² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21102111120493 and 21102111120502.

It is not a weakly prime, because it can be changed into another prime (21102111120551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551055560260 + 10551055560261.

It is an arithmetic number, because the mean of its divisors is an integer number (10551055560261).

Almost surely, 2^{21102111120521} is an apocalyptic number.

It is an amenable number.

21102111120521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102111120521 is an equidigital number, since it uses as much as digits as its factorization.

21102111120521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80, while the sum is 20.

Adding to 21102111120521 its reverse (12502111120112), we get a palindrome (33604222240633).

The spelling of 21102111120521 in words is "twenty-one trillion, one hundred two billion, one hundred eleven million, one hundred twenty thousand, five hundred twenty-one".