212721221 has 8 divisors (see below), whose sum is σ = 225973440. Its totient is φ = 199551168.

The previous prime is 212721217. The next prime is 212721241. The reversal of 212721221 is 122127212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 212721221 - 2² = 212721217 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 212721193 and 212721202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212721211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15161 + ... + 25598.

It is an arithmetic number, because the mean of its divisors is an integer number (28246680).

Almost surely, 2^212721221 is an apocalyptic number.

It is an amenable number.

212721221 is a deficient number, since it is larger than the sum of its proper divisors (13252219).

212721221 is a wasteful number, since it uses less digits than its factorization.

212721221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41083.

The product of its digits is 224, while the sum is 20.

The square root of 212721221 is about 14584.9655810358. The cubic root of 212721221 is about 596.9486014370.

Adding to 212721221 its reverse (122127212), we get a palindrome (334848433).

The spelling of 212721221 in words is "two hundred twelve million, seven hundred twenty-one thousand, two hundred twenty-one".