21123134009 has 2 divisors, whose sum is σ = 21123134010. Its totient is φ = 21123134008.

The previous prime is 21123134003. The next prime is 21123134069. The reversal of 21123134009 is 90043132112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19167018025 + 1956115984 = 138445^2 + 44228^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123134009 - 2²⁴ = 21106356793 is a prime.

It is not a weakly prime, because it can be changed into another prime (21123134003) 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, 10561567004 + 10561567005.

It is an arithmetic number, because the mean of its divisors is an integer number (10561567005).

Almost surely, 2^21123134009 is an apocalyptic number.

It is an amenable number.

21123134009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123134009 is an equidigital number, since it uses as much as digits as its factorization.

21123134009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 26.

The spelling of 21123134009 in words is "twenty-one billion, one hundred twenty-three million, one hundred thirty-four thousand, nine".