21220121002009 has 2 divisors, whose sum is σ = 21220121002010. Its totient is φ = 21220121002008.

The previous prime is 21220121002001. The next prime is 21220121002019. The reversal of 21220121002009 is 90020012102212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16969431643609 + 4250689358400 = 4119397^2 + 2061720^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220121002009 - 2³ = 21220121002001 is a prime.

It is not a weakly prime, because it can be changed into another prime (21220121002001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610060501004 + 10610060501005.

It is an arithmetic number, because the mean of its divisors is an integer number (10610060501005).

Almost surely, 2^{21220121002009} is an apocalyptic number.

It is an amenable number.

21220121002009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220121002009 is an equidigital number, since it uses as much as digits as its factorization.

21220121002009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 22.

The spelling of 21220121002009 in words is "twenty-one trillion, two hundred twenty billion, one hundred twenty-one million, two thousand, nine".