2001220261 has 2 divisors, whose sum is σ = 2001220262. Its totient is φ = 2001220260.

The previous prime is 2001220211. The next prime is 2001220267. The reversal of 2001220261 is 1620221002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2001220225 + 36 = 44735^2 + 6^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001220261 - 2⁹ = 2001219749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2001220267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000610130 + 1000610131.

It is an arithmetic number, because the mean of its divisors is an integer number (1000610131).

Almost surely, 2^2001220261 is an apocalyptic number.

It is an amenable number.

2001220261 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001220261 is an equidigital number, since it uses as much as digits as its factorization.

2001220261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 2001220261 is about 44735.0004023695. Note that the first 3 decimals coincide. The cubic root of 2001220261 is about 1260.1772365529.

Adding to 2001220261 its reverse (1620221002), we get a palindrome (3621441263).

The spelling of 2001220261 in words is "two billion, one million, two hundred twenty thousand, two hundred sixty-one".