2001020021 has 16 divisors (see below), whose sum is σ = 2686685568. Its totient is φ = 1439294400.

The previous prime is 2001019997. The next prime is 2001020029. The reversal of 2001020021 is 1200201002.

It is a cyclic number.

It is not a de Polignac number, because 2001020021 - 2⁶ = 2001019957 is a prime.

It is a super-2 number, since 2×2001020021² = 8008162248885680882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 2001019990 and 2001020008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001020029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 998510 + ... + 1000511.

It is an arithmetic number, because the mean of its divisors is an integer number (167917848).

Almost surely, 2^2001020021 is an apocalyptic number.

It is an amenable number.

2001020021 is a deficient number, since it is larger than the sum of its proper divisors (685665547).

2001020021 is a wasteful number, since it uses less digits than its factorization.

2001020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1999052.

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

The square root of 2001020021 is about 44732.7622777758. The cubic root of 2001020021 is about 1260.1352044802.

Adding to 2001020021 its reverse (1200201002), we get a palindrome (3201221023).

The spelling of 2001020021 in words is "two billion, one million, twenty thousand, twenty-one".