2001021020021 has 4 divisors (see below), whose sum is σ = 2001036295692. Its totient is φ = 2001005744352.

The previous prime is 2001021020003. The next prime is 2001021020023. The reversal of 2001021020021 is 1200201201002.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 339084936100 + 1661936083921 = 582310^2 + 1289161^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2001021020021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2001021019984 and 2001021020011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001021020023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7439630 + ... + 7703903.

It is an arithmetic number, because the mean of its divisors is an integer number (500259073923).

Almost surely, 2^{2001021020021} is an apocalyptic number.

It is an amenable number.

2001021020021 is a deficient number, since it is larger than the sum of its proper divisors (15275671).

2001021020021 is a wasteful number, since it uses less digits than its factorization.

2001021020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15275670.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 2001021020021 its reverse (1200201201002), we get a palindrome (3201222221023).

The spelling of 2001021020021 in words is "two trillion, one billion, twenty-one million, twenty thousand, twenty-one".