21230002121 has 2 divisors, whose sum is σ = 21230002122. Its totient is φ = 21230002120.

The previous prime is 21230002099. The next prime is 21230002153. The reversal of 21230002121 is 12120003212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15120391225 + 6109610896 = 122965^2 + 78164^2 .

It is a cyclic number.

It is not a de Polignac number, because 21230002121 - 2¹⁴ = 21229985737 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21230002096 and 21230002105.

It is not a weakly prime, because it can be changed into another prime (21230002021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615001060 + 10615001061.

It is an arithmetic number, because the mean of its divisors is an integer number (10615001061).

Almost surely, 2^21230002121 is an apocalyptic number.

It is an amenable number.

21230002121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21230002121 is an equidigital number, since it uses as much as digits as its factorization.

21230002121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21230002121 its reverse (12120003212), we get a palindrome (33350005333).

The spelling of 21230002121 in words is "twenty-one billion, two hundred thirty million, two thousand, one hundred twenty-one".