21020011 has 2 divisors, whose sum is σ = 21020012. Its totient is φ = 21020010.

The previous prime is 21019993. The next prime is 21020017. The reversal of 21020011 is 11002012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21020011 - 2⁵ = 21019979 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21019976 and 21020003.

It is not a weakly prime, because it can be changed into another prime (21020017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510005 + 10510006.

It is an arithmetic number, because the mean of its divisors is an integer number (10510006).

Almost surely, 2^21020011 is an apocalyptic number.

21020011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020011 is an equidigital number, since it uses as much as digits as its factorization.

21020011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21020011 is about 4584.7585541662. The cubic root of 21020011 is about 275.9800228837.

Adding to 21020011 its reverse (11002012), we get a palindrome (32022023).

The spelling of 21020011 in words is "twenty-one million, twenty thousand, eleven".