21104200121 has 2 divisors, whose sum is σ = 21104200122. Its totient is φ = 21104200120.

The previous prime is 21104200111. The next prime is 21104200147. The reversal of 21104200121 is 12100240112.

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., 15149917225 + 5954282896 = 123085^2 + 77164^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21104200121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21104200096 and 21104200105.

It is not a weakly prime, because it can be changed into another prime (21104200111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10552100060 + 10552100061.

It is an arithmetic number, because the mean of its divisors is an integer number (10552100061).

Almost surely, 2^21104200121 is an apocalyptic number.

It is an amenable number.

21104200121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21104200121 is an equidigital number, since it uses as much as digits as its factorization.

21104200121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21104200121 its reverse (12100240112), we get a palindrome (33204440233).

The spelling of 21104200121 in words is "twenty-one billion, one hundred four million, two hundred thousand, one hundred twenty-one".