21001000002121 has 2 divisors, whose sum is σ = 21001000002122. Its totient is φ = 21001000002120.

The previous prime is 21001000002097. The next prime is 21001000002137. The reversal of 21001000002121 is 12120000010012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19719496760896 + 1281503241225 = 4440664^2 + 1132035^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001000002121 - 2¹¹ = 21001000000073 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001000002098 and 21001000002107.

It is not a weakly prime, because it can be changed into another prime (21001000002821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500500001060 + 10500500001061.

It is an arithmetic number, because the mean of its divisors is an integer number (10500500001061).

Almost surely, 2^{21001000002121} is an apocalyptic number.

It is an amenable number.

21001000002121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001000002121 is an equidigital number, since it uses as much as digits as its factorization.

21001000002121 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 10.

Adding to 21001000002121 its reverse (12120000010012), we get a palindrome (33121000012133).

The spelling of 21001000002121 in words is "twenty-one trillion, one billion, two thousand, one hundred twenty-one".