2001121261 has 2 divisors, whose sum is σ = 2001121262. Its totient is φ = 2001121260.

The previous prime is 2001121259. The next prime is 2001121313. The reversal of 2001121261 is 1621211002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1681820100 + 319301161 = 41010^2 + 17869^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001121261 - 2¹ = 2001121259 is a prime.

Together with 2001121259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2001121861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000560630 + 1000560631.

It is an arithmetic number, because the mean of its divisors is an integer number (1000560631).

Almost surely, 2^2001121261 is an apocalyptic number.

It is an amenable number.

2001121261 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001121261 is an equidigital number, since it uses as much as digits as its factorization.

2001121261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 2001121261 is about 44733.8938725437. The cubic root of 2001121261 is about 1260.1564559645.

Adding to 2001121261 its reverse (1621211002), we get a palindrome (3622332263).

The spelling of 2001121261 in words is "two billion, one million, one hundred twenty-one thousand, two hundred sixty-one".