21221011001209 has 16 divisors (see below), whose sum is σ = 22476200293008. Its totient is φ = 19966588895232.

The previous prime is 21221011001173. The next prime is 21221011001213. The reversal of 21221011001209 is 90210011012212.

It can be written as a sum of positive squares in 8 ways, for example, as 1847280567609 + 19373730433600 = 1359147^2 + 4401560^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221011001209 - 2⁷ = 21221011001081 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21221011001209.

It is not an unprimeable number, because it can be changed into a prime (21221011001279) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1241494467 + ... + 1241511559.

It is an arithmetic number, because the mean of its divisors is an integer number (1404762518313).

Almost surely, 2^{21221011001209} is an apocalyptic number.

It is an amenable number.

21221011001209 is a deficient number, since it is larger than the sum of its proper divisors (1255189291799).

21221011001209 is a wasteful number, since it uses less digits than its factorization.

21221011001209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35244.

The product of its (nonzero) digits is 144, while the sum is 22.

The spelling of 21221011001209 in words is "twenty-one trillion, two hundred twenty-one billion, eleven million, one thousand, two hundred nine".