21103021 has 2 divisors, whose sum is σ = 21103022. Its totient is φ = 21103020.

The previous prime is 21103003. The next prime is 21103051. The reversal of 21103021 is 12030112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21058921 + 44100 = 4589^2 + 210^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103021 - 2¹⁷ = 20971949 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21102989 and 21103007.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21103051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551510 + 10551511.

It is an arithmetic number, because the mean of its divisors is an integer number (10551511).

Almost surely, 2^21103021 is an apocalyptic number.

It is an amenable number.

21103021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103021 is an equidigital number, since it uses as much as digits as its factorization.

21103021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21103021 is about 4593.8024554828. The cubic root of 21103021 is about 276.3428360614.

Adding to 21103021 its reverse (12030112), we get a palindrome (33133133).

The spelling of 21103021 in words is "twenty-one million, one hundred three thousand, twenty-one".