210021220021 has 16 divisors (see below), whose sum is σ = 230358809520. Its totient is φ = 190679019520.

The previous prime is 210021220009. The next prime is 210021220033. The reversal of 210021220021 is 120022120012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (210021220009) and next prime (210021220033).

It can be written as a sum of positive squares in 8 ways, for example, as 70642197796 + 139379022225 = 265786^2 + 373335^2 .

It is a cyclic number.

It is not a de Polignac number, because 210021220021 - 2⁷ = 210021219893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 210021219983 and 210021220010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210021220051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1630786 + ... + 1754851.

It is an arithmetic number, because the mean of its divisors is an integer number (14397425595).

Almost surely, 2^210021220021 is an apocalyptic number.

It is an amenable number.

210021220021 is a deficient number, since it is larger than the sum of its proper divisors (20337589499).

210021220021 is a wasteful number, since it uses less digits than its factorization.

210021220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3385784.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 210021220021 its reverse (120022120012), we get a palindrome (330043340033).

The spelling of 210021220021 in words is "two hundred ten billion, twenty-one million, two hundred twenty thousand, twenty-one".