21111202072021 has 2 divisors, whose sum is σ = 21111202072022. Its totient is φ = 21111202072020.

The previous prime is 21111202071977. The next prime is 21111202072031. The reversal of 21111202072021 is 12027020211112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15216435680625 + 5894766391396 = 3900825^2 + 2427914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111202072021 - 2¹⁷ = 21111201940949 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21111202071983 and 21111202072001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111202072031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555601036010 + 10555601036011.

It is an arithmetic number, because the mean of its divisors is an integer number (10555601036011).

Almost surely, 2^{21111202072021} is an apocalyptic number.

It is an amenable number.

21111202072021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111202072021 is an equidigital number, since it uses as much as digits as its factorization.

21111202072021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 224, while the sum is 22.

Adding to 21111202072021 its reverse (12027020211112), we get a palindrome (33138222283133).

The spelling of 21111202072021 in words is "twenty-one trillion, one hundred eleven billion, two hundred two million, seventy-two thousand, twenty-one".