21056116129 has 2 divisors, whose sum is σ = 21056116130. Its totient is φ = 21056116128.

The previous prime is 21056116099. The next prime is 21056116157. The reversal of 21056116129 is 92161165012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20685630625 + 370485504 = 143825^2 + 19248^2 .

It is a cyclic number.

It is not a de Polignac number, because 21056116129 - 2²¹ = 21054018977 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21056116094 and 21056116103.

It is not a weakly prime, because it can be changed into another prime (21056116229) 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, 10528058064 + 10528058065.

It is an arithmetic number, because the mean of its divisors is an integer number (10528058065).

Almost surely, 2^21056116129 is an apocalyptic number.

It is an amenable number.

21056116129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056116129 is an equidigital number, since it uses as much as digits as its factorization.

21056116129 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 34.

The spelling of 21056116129 in words is "twenty-one billion, fifty-six million, one hundred sixteen thousand, one hundred twenty-nine".