2001221200021 has 4 divisors (see below), whose sum is σ = 2010037152672. Its totient is φ = 1992405247372.

The previous prime is 2001221200019. The next prime is 2001221200049. The reversal of 2001221200021 is 1200021221002.

It is a happy number.

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 2001221200021 - 2¹ = 2001221200019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2001221199974 and 2001221200010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001221200061) 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, 4407975985 + ... + 4407976438.

It is an arithmetic number, because the mean of its divisors is an integer number (502509288168).

Almost surely, 2^{2001221200021} is an apocalyptic number.

It is an amenable number.

2001221200021 is a deficient number, since it is larger than the sum of its proper divisors (8815952651).

2001221200021 is an equidigital number, since it uses as much as digits as its factorization.

2001221200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8815952650.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 2001221200021 its reverse (1200021221002), we get a palindrome (3201242421023).

The spelling of 2001221200021 in words is "two trillion, one billion, two hundred twenty-one million, two hundred thousand, twenty-one".