21124133209 has 2 divisors, whose sum is σ = 21124133210. Its totient is φ = 21124133208.

The previous prime is 21124133137. The next prime is 21124133231. The reversal of 21124133209 is 90233142112.

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., 21116449225 + 7683984 = 145315^2 + 2772^2 .

It is a cyclic number.

It is not a de Polignac number, because 21124133209 - 2¹⁹ = 21123608921 is a prime.

It is not a weakly prime, because it can be changed into another prime (21124133249) 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, 10562066604 + 10562066605.

It is an arithmetic number, because the mean of its divisors is an integer number (10562066605).

Almost surely, 2^21124133209 is an apocalyptic number.

It is an amenable number.

21124133209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21124133209 is an equidigital number, since it uses as much as digits as its factorization.

21124133209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 28.

The spelling of 21124133209 in words is "twenty-one billion, one hundred twenty-four million, one hundred thirty-three thousand, two hundred nine".