2100200021 has 4 divisors (see below), whose sum is σ = 2102432844. Its totient is φ = 2097967200.

The previous prime is 2100199987. The next prime is 2100200051. The reversal of 2100200021 is 1200020012.

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 946239121 + 1153960900 = 30761^2 + 33970^2 .

It is a cyclic number.

It is not a de Polignac number, because 2100200021 - 2²⁶ = 2033091157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2100199981 and 2100200008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2100200051) 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, 1115000 + ... + 1116881.

It is an arithmetic number, because the mean of its divisors is an integer number (525608211).

Almost surely, 2^2100200021 is an apocalyptic number.

It is an amenable number.

2100200021 is a deficient number, since it is larger than the sum of its proper divisors (2232823).

2100200021 is an equidigital number, since it uses as much as digits as its factorization.

2100200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2232822.

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

The square root of 2100200021 is about 45827.9393056245. The cubic root of 2100200021 is about 1280.6198212721.

Adding to 2100200021 its reverse (1200020012), we get a palindrome (3300220033).

Subtracting from 2100200021 its reverse (1200020012), we obtain a square (900180009 = 30003²).

The spelling of 2100200021 in words is "two billion, one hundred million, two hundred thousand, twenty-one".