21126929 has 2 divisors, whose sum is σ = 21126930. Its totient is φ = 21126928.

The previous prime is 21126901. The next prime is 21126943. The reversal of 21126929 is 92962112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11235904 + 9891025 = 3352^2 + 3145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21126929 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21126895 and 21126904.

It is not a weakly prime, because it can be changed into another prime (21126229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10563464 + 10563465.

It is an arithmetic number, because the mean of its divisors is an integer number (10563465).

Almost surely, 2^21126929 is an apocalyptic number.

It is an amenable number.

21126929 is a deficient number, since it is larger than the sum of its proper divisors (1).

21126929 is an equidigital number, since it uses as much as digits as its factorization.

21126929 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 32.

The square root of 21126929 is about 4596.4039204578. The cubic root of 21126929 is about 276.4471546342.

The spelling of 21126929 in words is "twenty-one million, one hundred twenty-six thousand, nine hundred twenty-nine".