212721804221 has 4 divisors (see below), whose sum is σ = 212895739872. Its totient is φ = 212547868572.

The previous prime is 212721804209. The next prime is 212721804223. The reversal of 212721804221 is 122408127212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 212721804221 - 2⁶ = 212721804157 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 (212721804223) 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, 86965991 + ... + 86968436.

It is an arithmetic number, because the mean of its divisors is an integer number (53223934968).

Almost surely, 2^212721804221 is an apocalyptic number.

It is an amenable number.

212721804221 is a deficient number, since it is larger than the sum of its proper divisors (173935651).

212721804221 is a wasteful number, since it uses less digits than its factorization.

212721804221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173935650.

The product of its (nonzero) digits is 7168, while the sum is 32.

The spelling of 212721804221 in words is "two hundred twelve billion, seven hundred twenty-one million, eight hundred four thousand, two hundred twenty-one".