212100010021 has 4 divisors (see below), whose sum is σ = 219413803500. Its totient is φ = 204786216544.

The previous prime is 212100010019. The next prime is 212100010061. The reversal of 212100010021 is 120010001212.

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 130996944225 + 81103065796 = 361935^2 + 284786^2 .

It is a cyclic number.

It is not a de Polignac number, because 212100010021 - 2¹ = 212100010019 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 (212100010061) 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, 3656896696 + ... + 3656896753.

It is an arithmetic number, because the mean of its divisors is an integer number (54853450875).

Almost surely, 2^212100010021 is an apocalyptic number.

It is an amenable number.

212100010021 is a deficient number, since it is larger than the sum of its proper divisors (7313793479).

212100010021 is an equidigital number, since it uses as much as digits as its factorization.

212100010021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7313793478.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 212100010021 its reverse (120010001212), we get a palindrome (332110011233).

The spelling of 212100010021 in words is "two hundred twelve billion, one hundred million, ten thousand, twenty-one".