2101200021 has 40 divisors (see below), whose sum is σ = 3251971800. Its totient is φ = 1351088640.

The previous prime is 2101200019. The next prime is 2101200037. The reversal of 2101200021 is 1200021012.

It can be written as a sum of positive squares in 4 ways, for example, as 132503121 + 1968696900 = 11511^2 + 44370^2 .

It is not a de Polignac number, because 2101200021 - 2¹ = 2101200019 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 = 2101199976 and 2101200012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2101200011) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 292015 + ... + 299123.

It is an arithmetic number, because the mean of its divisors is an integer number (81299295).

Almost surely, 2^2101200021 is an apocalyptic number.

It is an amenable number.

2101200021 is a deficient number, since it is larger than the sum of its proper divisors (1150771779).

2101200021 is an equidigital number, since it uses as much as digits as its factorization.

2101200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7251 (or 7242 counting only the distinct ones).

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

The square root of 2101200021 is about 45838.8483821311. The cubic root of 2101200021 is about 1280.8230426492.

Adding to 2101200021 its reverse (1200021012), we get a palindrome (3301221033).

The spelling of 2101200021 in words is "two billion, one hundred one million, two hundred thousand, twenty-one".