2100100021 has 4 divisors (see below), whose sum is σ = 2119727232. Its totient is φ = 2080472812.

The previous prime is 2100099979. The next prime is 2100100033. The reversal of 2100100021 is 1200010012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2100100021 - 2¹⁵ = 2100067253 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2100099977 and 2100100013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2100100081) 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, 9813445 + ... + 9813658.

It is an arithmetic number, because the mean of its divisors is an integer number (529931808).

Almost surely, 2^2100100021 is an apocalyptic number.

It is an amenable number.

2100100021 is a deficient number, since it is larger than the sum of its proper divisors (19627211).

2100100021 is a wasteful number, since it uses less digits than its factorization.

2100100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19627210.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 2100100021 is about 45826.8482551441. The cubic root of 2100100021 is about 1280.5994955867.

Adding to 2100100021 its reverse (1200010012), we get a palindrome (3300110033).

Subtracting from 2100100021 its reverse (1200010012), we obtain a palindrome (900090009).

The spelling of 2100100021 in words is "two billion, one hundred million, one hundred thousand, twenty-one".