2001120021 has 24 divisors (see below), whose sum is σ = 2937263264. Its totient is φ = 1312549920.

The previous prime is 2001120013. The next prime is 2001120047. The reversal of 2001120021 is 1200211002.

It is not a de Polignac number, because 2001120021 - 2³ = 2001120013 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2001119985 and 2001120012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001120001) 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 23 ways as a sum of consecutive naturals, for example, 672066 + ... + 675036.

Almost surely, 2^2001120021 is an apocalyptic number.

It is an amenable number.

2001120021 is a deficient number, since it is larger than the sum of its proper divisors (936143243).

2001120021 is a wasteful number, since it uses less digits than its factorization.

2001120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4161 (or 4158 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 2001120021 is about 44733.8800128046. The cubic root of 2001120021 is about 1260.1561956780.

Adding to 2001120021 its reverse (1200211002), we get a palindrome (3201331023).

The spelling of 2001120021 in words is "two billion, one million, one hundred twenty thousand, twenty-one".