2001221221021 has 4 divisors (see below), whose sum is σ = 2183150422944. Its totient is φ = 1819292019100.

The previous prime is 2001221220989. The next prime is 2001221221037. The reversal of 2001221221021 is 1201221221002.

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 2001221221021 - 2⁵ = 2001221220989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2001221220986 and 2001221221004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001221221121) 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, 90964600945 + ... + 90964600966.

It is an arithmetic number, because the mean of its divisors is an integer number (545787605736).

Almost surely, 2^{2001221221021} is an apocalyptic number.

It is an amenable number.

2001221221021 is a deficient number, since it is larger than the sum of its proper divisors (181929201923).

2001221221021 is a wasteful number, since it uses less digits than its factorization.

2001221221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181929201922.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 2001221221021 its reverse (1201221221002), we get a palindrome (3202442442023).

It can be divided in two parts, 200 and 1221221021, that added together give a palindrome (1221221221).

The spelling of 2001221221021 in words is "two trillion, one billion, two hundred twenty-one million, two hundred twenty-one thousand, twenty-one".