210100000021 has 4 divisors (see below), whose sum is σ = 211017467500. Its totient is φ = 209182532544.

The previous prime is 210100000001. The next prime is 210100000031. The reversal of 210100000021 is 120000001012.

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 102457608100 + 107642391921 = 320090^2 + 328089^2 .

It is a cyclic number.

It is not a de Polignac number, because 210100000021 - 2¹¹ = 210099997973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210100000001) 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, 458733396 + ... + 458733853.

It is an arithmetic number, because the mean of its divisors is an integer number (52754366875).

Almost surely, 2^210100000021 is an apocalyptic number.

It is an amenable number.

210100000021 is a deficient number, since it is larger than the sum of its proper divisors (917467479).

210100000021 is an equidigital number, since it uses as much as digits as its factorization.

210100000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 917467478.

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

Adding to 210100000021 its reverse (120000001012), we get a palindrome (330100001033).

Subtracting from 210100000021 its reverse (120000001012), we obtain a palindrome (90099999009).

The spelling of 210100000021 in words is "two hundred ten billion, one hundred million, twenty-one", and thus it is an aban number.