21020120110021 has 2 divisors, whose sum is σ = 21020120110022. Its totient is φ = 21020120110020.

The previous prime is 21020120110001. The next prime is 21020120110051. The reversal of 21020120110021 is 12001102102012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18593257760100 + 2426862349921 = 4311990^2 + 1557839^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21020120110021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020120109983 and 21020120110010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21020120110001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510060055010 + 10510060055011.

It is an arithmetic number, because the mean of its divisors is an integer number (10510060055011).

Almost surely, 2^{21020120110021} is an apocalyptic number.

It is an amenable number.

21020120110021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020120110021 is an equidigital number, since it uses as much as digits as its factorization.

21020120110021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21020120110021 its reverse (12001102102012), we get a palindrome (33021222212033).

The spelling of 21020120110021 in words is "twenty-one trillion, twenty billion, one hundred twenty million, one hundred ten thousand, twenty-one".