211100021221 has 4 divisors (see below), whose sum is σ = 211144627692. Its totient is φ = 211055414752.

The previous prime is 211100021213. The next prime is 211100021261. The reversal of 211100021221 is 122120001112.

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 144788621121 + 66311400100 = 380511^2 + 257510^2 .

It is a cyclic number.

It is not a de Polignac number, because 211100021221 - 2³ = 211100021213 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 (211100021201) 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, 22296136 + ... + 22305601.

It is an arithmetic number, because the mean of its divisors is an integer number (52786156923).

Almost surely, 2^211100021221 is an apocalyptic number.

It is an amenable number.

211100021221 is a deficient number, since it is larger than the sum of its proper divisors (44606471).

211100021221 is an equidigital number, since it uses as much as digits as its factorization.

211100021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44606470.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 211100021221 its reverse (122120001112), we get a palindrome (333220022333).

The spelling of 211100021221 in words is "two hundred eleven billion, one hundred million, twenty-one thousand, two hundred twenty-one".