21201000000121 has 2 divisors, whose sum is σ = 21201000000122. Its totient is φ = 21201000000120.

The previous prime is 21201000000101. The next prime is 21201000000181. The reversal of 21201000000121 is 12100000010212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20149226686521 + 1051773313600 = 4488789^2 + 1025560^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201000000121 - 2¹⁹ = 21200999475833 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201000000098 and 21201000000107.

It is not a weakly prime, because it can be changed into another prime (21201000000101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600500000060 + 10600500000061.

It is an arithmetic number, because the mean of its divisors is an integer number (10600500000061).

Almost surely, 2^{21201000000121} is an apocalyptic number.

It is an amenable number.

21201000000121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201000000121 is an equidigital number, since it uses as much as digits as its factorization.

21201000000121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21201000000121 its reverse (12100000010212), we get a palindrome (33301000010333).

The spelling of 21201000000121 in words is "twenty-one trillion, two hundred one billion, one hundred twenty-one", and thus it is an aban number.