21002001122009 has 2 divisors, whose sum is σ = 21002001122010. Its totient is φ = 21002001122008.

The previous prime is 21002001121999. The next prime is 21002001122023. The reversal of 21002001122009 is 90022110020012.

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., 14093619697609 + 6908381424400 = 3754147^2 + 2628380^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002001122009 - 2²⁸ = 21001732686553 is a prime.

It is a super-2 number, since 2×21002001122009² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21002001122309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501000561004 + 10501000561005.

It is an arithmetic number, because the mean of its divisors is an integer number (10501000561005).

Almost surely, 2^{21002001122009} is an apocalyptic number.

It is an amenable number.

21002001122009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002001122009 is an equidigital number, since it uses as much as digits as its factorization.

21002001122009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 20.

The spelling of 21002001122009 in words is "twenty-one trillion, two billion, one million, one hundred twenty-two thousand, nine".