21011221129 has 2 divisors, whose sum is σ = 21011221130. Its totient is φ = 21011221128.

The previous prime is 21011221097. The next prime is 21011221141. The reversal of 21011221129 is 92112211012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18700015504 + 2311205625 = 136748^2 + 48075^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011221129 - 2⁵ = 21011221097 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011221529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505610564 + 10505610565.

It is an arithmetic number, because the mean of its divisors is an integer number (10505610565).

Almost surely, 2^21011221129 is an apocalyptic number.

It is an amenable number.

21011221129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011221129 is an equidigital number, since it uses as much as digits as its factorization.

21011221129 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 22.

The spelling of 21011221129 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, one hundred twenty-nine".