2021001021 has 24 divisors (see below), whose sum is σ = 3328710840. Its totient is φ = 1170533376.

The previous prime is 2021001001. The next prime is 2021001041. The reversal of 2021001021 is 1201001202.

It is an interprime number because it is at equal distance from previous prime (2021001001) and next prime (2021001041).

It can be written as a sum of positive squares in 4 ways, for example, as 904505625 + 1116495396 = 30075^2 + 33414^2 .

It is not a de Polignac number, because 2021001021 - 2⁶ = 2021000957 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 2021000994 and 2021001012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2021001001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 506056 + ... + 510033.

It is an arithmetic number, because the mean of its divisors is an integer number (138696285).

Almost surely, 2^2021001021 is an apocalyptic number.

It is an amenable number.

2021001021 is a deficient number, since it is larger than the sum of its proper divisors (1307709819).

2021001021 is a wasteful number, since it uses less digits than its factorization.

2021001021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1016125 (or 1016122 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 2021001021 is about 44955.5449416421. The cubic root of 2021001021 is about 1264.3156418519.

Adding to 2021001021 its reverse (1201001202), we get a palindrome (3222002223).

The spelling of 2021001021 in words is "two billion, twenty-one million, one thousand, twenty-one".