2001220021 has 4 divisors (see below), whose sum is σ = 2026552000. Its totient is φ = 1975888044.

The previous prime is 2001220019. The next prime is 2001220027. The reversal of 2001220021 is 1200221002.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2001220021 - 2¹ = 2001220019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001220027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12665871 + ... + 12666028.

It is an arithmetic number, because the mean of its divisors is an integer number (506638000).

Almost surely, 2^2001220021 is an apocalyptic number.

It is an amenable number.

2001220021 is a deficient number, since it is larger than the sum of its proper divisors (25331979).

2001220021 is an equidigital number, since it uses as much as digits as its factorization.

2001220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25331978.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 2001220021 is about 44734.9977199061. The cubic root of 2001220021 is about 1260.1771861765.

Adding to 2001220021 its reverse (1200221002), we get a palindrome (3201441023).

It can be divided in two parts, 200 and 1220021, that added together give a palindrome (1220221).

The spelling of 2001220021 in words is "two billion, one million, two hundred twenty thousand, twenty-one".