21122111009 has 2 divisors, whose sum is σ = 21122111010. Its totient is φ = 21122111008.

The previous prime is 21122110981. The next prime is 21122111047. The reversal of 21122111009 is 90011122112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20593111009 + 529000000 = 143503^2 + 23000^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122111009 - 2¹² = 21122106913 is a prime.

It is a super-2 number, since 2×21122111009² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21122111089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561055504 + 10561055505.

It is an arithmetic number, because the mean of its divisors is an integer number (10561055505).

Almost surely, 2^21122111009 is an apocalyptic number.

It is an amenable number.

21122111009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122111009 is an equidigital number, since it uses as much as digits as its factorization.

21122111009 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 20.

The spelling of 21122111009 in words is "twenty-one billion, one hundred twenty-two million, one hundred eleven thousand, nine".