2001221101909 has 2 divisors, whose sum is σ = 2001221101910. Its totient is φ = 2001221101908.

The previous prime is 2001221101897. The next prime is 2001221101949. The reversal of 2001221101909 is 9091011221002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2000465126884 + 755975025 = 1414378^2 + 27495^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001221101909 - 2¹³ = 2001221093717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2001221101949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000610550954 + 1000610550955.

It is an arithmetic number, because the mean of its divisors is an integer number (1000610550955).

Almost surely, 2^{2001221101909} is an apocalyptic number.

It is an amenable number.

2001221101909 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001221101909 is an equidigital number, since it uses as much as digits as its factorization.

2001221101909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 28.

It can be divided in two parts, 200122 and 1101909, that added together give a palindrome (1302031).

The spelling of 2001221101909 in words is "two trillion, one billion, two hundred twenty-one million, one hundred one thousand, nine hundred nine".