210121100021 has 16 divisors (see below), whose sum is σ = 244711857024. Its totient is φ = 176674889664.

The previous prime is 210121100011. The next prime is 210121100027. The reversal of 210121100021 is 120001121012.

210121100021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 210121100021 - 2¹⁸ = 210120837877 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 210121099975 and 210121100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210121100027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2229170 + ... + 2321516.

It is an arithmetic number, because the mean of its divisors is an integer number (15294491064).

Almost surely, 2^210121100021 is an apocalyptic number.

It is an amenable number.

210121100021 is a deficient number, since it is larger than the sum of its proper divisors (34590757003).

210121100021 is an equidigital number, since it uses as much as digits as its factorization.

210121100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98540.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 210121100021 its reverse (120001121012), we get a palindrome (330122221033).

The spelling of 210121100021 in words is "two hundred ten billion, one hundred twenty-one million, one hundred thousand, twenty-one".