21035500121 has 2 divisors, whose sum is σ = 21035500122. Its totient is φ = 21035500120.

The previous prime is 21035500099. The next prime is 21035500253. The reversal of 21035500121 is 12100553012.

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., 21021810121 + 13690000 = 144989^2 + 3700^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21035500121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21035500093 and 21035500102.

It is not a weakly prime, because it can be changed into another prime (21035500021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10517750060 + 10517750061.

It is an arithmetic number, because the mean of its divisors is an integer number (10517750061).

Almost surely, 2^21035500121 is an apocalyptic number.

It is an amenable number.

21035500121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21035500121 is an equidigital number, since it uses as much as digits as its factorization.

21035500121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 20.

The spelling of 21035500121 in words is "twenty-one billion, thirty-five million, five hundred thousand, one hundred twenty-one".