21002111021 has 2 divisors, whose sum is σ = 21002111022. Its totient is φ = 21002111020.

The previous prime is 21002110973. The next prime is 21002111029. The reversal of 21002111021 is 12011120012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19505194921 + 1496916100 = 139661^2 + 38690^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002111021 - 2²² = 20997916717 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21002110993 and 21002111011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002111029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501055510 + 10501055511.

It is an arithmetic number, because the mean of its divisors is an integer number (10501055511).

Almost surely, 2^21002111021 is an apocalyptic number.

It is an amenable number.

21002111021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002111021 is an equidigital number, since it uses as much as digits as its factorization.

21002111021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21002111021 its reverse (12011120012), we get a palindrome (33013231033).

The spelling of 21002111021 in words is "twenty-one billion, two million, one hundred eleven thousand, twenty-one".