2102001021 has 24 divisors (see below), whose sum is σ = 3086474040. Its totient is φ = 1378308096.

The previous prime is 2102001007. The next prime is 2102001029. The reversal of 2102001021 is 1201002012.

It can be written as a sum of positive squares in 4 ways, for example, as 46376100 + 2055624921 = 6810^2 + 45339^2 .

It is not a de Polignac number, because 2102001021 - 2¹⁹ = 2101476733 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 = 2102000994 and 2102001012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2102001029) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 147795 + ... + 161391.

It is an arithmetic number, because the mean of its divisors is an integer number (128603085).

Almost surely, 2^2102001021 is an apocalyptic number.

It is an amenable number.

2102001021 is a deficient number, since it is larger than the sum of its proper divisors (984473019).

2102001021 is a wasteful number, since it uses less digits than its factorization.

2102001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13885 (or 13882 counting only the distinct ones).

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

The square root of 2102001021 is about 45847.5846801116. The cubic root of 2102001021 is about 1280.9857764693.

Adding to 2102001021 its reverse (1201002012), we get a palindrome (3303003033).

Subtracting from 2102001021 its reverse (1201002012), we obtain a palindrome (900999009).

The spelling of 2102001021 in words is "two billion, one hundred two million, one thousand, twenty-one".