21011122009 has 2 divisors, whose sum is σ = 21011122010. Its totient is φ = 21011122008.

The previous prime is 21011121979. The next prime is 21011122049. The reversal of 21011122009 is 90022111012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17563670784 + 3447451225 = 132528^2 + 58715^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011122009 - 2²⁵ = 20977567577 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011122049) 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, 10505561004 + 10505561005.

It is an arithmetic number, because the mean of its divisors is an integer number (10505561005).

Almost surely, 2^21011122009 is an apocalyptic number.

It is an amenable number.

21011122009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011122009 is an equidigital number, since it uses as much as digits as its factorization.

21011122009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 21011122009 in words is "twenty-one billion, eleven million, one hundred twenty-two thousand, nine".