2001221091 has 12 divisors (see below), whose sum is σ = 2891338320. Its totient is φ = 1333830960.

The previous prime is 2001221077. The next prime is 2001221119. The reversal of 2001221091 is 1901221002.

It is not a de Polignac number, because 2001221091 - 2¹⁴ = 2001204707 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2001221071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17530 + ... + 65648.

It is an arithmetic number, because the mean of its divisors is an integer number (240944860).

Almost surely, 2^2001221091 is an apocalyptic number.

2001221091 is a deficient number, since it is larger than the sum of its proper divisors (890117229).

2001221091 is a wasteful number, since it uses less digits than its factorization.

2001221091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52746 (or 52743 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 2001221091 is about 44735.0096792210. The cubic root of 2001221091 is about 1260.1774107711.

Adding to 2001221091 its reverse (1901221002), we get a palindrome (3902442093).

It can be divided in two parts, 20012210 and 91, that added together give a triangular number (20012301 = T₆₃₂₆).

The spelling of 2001221091 in words is "two billion, one million, two hundred twenty-one thousand, ninety-one".