212211312221 has 4 divisors (see below), whose sum is σ = 215118316572. Its totient is φ = 209304307872.

The previous prime is 212211312217. The next prime is 212211312223. The reversal of 212211312221 is 122213112212.

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 144408360121 + 67802952100 = 380011^2 + 260390^2 .

It is a cyclic number.

It is not a de Polignac number, because 212211312221 - 2² = 212211312217 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212211312193 and 212211312202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212211312223) 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, 1453502066 + ... + 1453502211.

It is an arithmetic number, because the mean of its divisors is an integer number (53779579143).

Almost surely, 2^212211312221 is an apocalyptic number.

It is an amenable number.

212211312221 is a deficient number, since it is larger than the sum of its proper divisors (2907004351).

212211312221 is an equidigital number, since it uses as much as digits as its factorization.

212211312221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2907004350.

The product of its digits is 192, while the sum is 20.

Adding to 212211312221 its reverse (122213112212), we get a palindrome (334424424433).

Subtracting from 212211312221 its reverse (122213112212), we obtain a square (89998200009 = 299997²).

The spelling of 212211312221 in words is "two hundred twelve billion, two hundred eleven million, three hundred twelve thousand, two hundred twenty-one".