21101111021021 has 2 divisors, whose sum is σ = 21101111021022. Its totient is φ = 21101111021020.

The previous prime is 21101111020999. The next prime is 21101111021027. The reversal of 21101111021021 is 12012011110112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21054836988025 + 46274032996 = 4588555^2 + 215114^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21101111021021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21101111020987 and 21101111021005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21101111021027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550555510510 + 10550555510511.

It is an arithmetic number, because the mean of its divisors is an integer number (10550555510511).

Almost surely, 2^{21101111021021} is an apocalyptic number.

It is an amenable number.

21101111021021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21101111021021 is an equidigital number, since it uses as much as digits as its factorization.

21101111021021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8, while the sum is 14.

Adding to 21101111021021 its reverse (12012011110112), we get a palindrome (33113122131133).

The spelling of 21101111021021 in words is "twenty-one trillion, one hundred one billion, one hundred eleven million, twenty-one thousand, twenty-one".