21130010021 has 2 divisors, whose sum is σ = 21130010022. Its totient is φ = 21130010020.

The previous prime is 21130009993. The next prime is 21130010053. The reversal of 21130010021 is 12001003112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19631932996 + 1498077025 = 140114^2 + 38705^2 .

It is a cyclic number.

It is not a de Polignac number, because 21130010021 - 2¹⁴ = 21129993637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21130009984 and 21130010011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21130010521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565005010 + 10565005011.

It is an arithmetic number, because the mean of its divisors is an integer number (10565005011).

Almost surely, 2^21130010021 is an apocalyptic number.

It is an amenable number.

21130010021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130010021 is an equidigital number, since it uses as much as digits as its factorization.

21130010021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12, while the sum is 11.

Adding to 21130010021 its reverse (12001003112), we get a palindrome (33131013133).

The spelling of 21130010021 in words is "twenty-one billion, one hundred thirty million, ten thousand, twenty-one".