212100220021 has 4 divisors (see below), whose sum is σ = 212225502412. Its totient is φ = 211974937632.

The previous prime is 212100220001. The next prime is 212100220037. The reversal of 212100220021 is 120022001212.

It is a happy number.

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 105161409796 + 106938810225 = 324286^2 + 327015^2 .

It is a cyclic number.

It is not a de Polignac number, because 212100220021 - 2²¹ = 212098122869 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212100219983 and 212100220010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212100220001) 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, 62638656 + ... + 62642041.

It is an arithmetic number, because the mean of its divisors is an integer number (53056375603).

Almost surely, 2^212100220021 is an apocalyptic number.

It is an amenable number.

212100220021 is a deficient number, since it is larger than the sum of its proper divisors (125282391).

212100220021 is a wasteful number, since it uses less digits than its factorization.

212100220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125282390.

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

Adding to 212100220021 its reverse (120022001212), we get a palindrome (332122221233).

The spelling of 212100220021 in words is "two hundred twelve billion, one hundred million, two hundred twenty thousand, twenty-one".