211212221 has 8 divisors (see below), whose sum is σ = 230918688. Its totient is φ = 191590000.

The previous prime is 211212203. The next prime is 211212241. The reversal of 211212221 is 122212112.

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

It is a cyclic number.

It is not a de Polignac number, because 211212221 - 2²⁶ = 144103357 is a prime.

It is a super-2 number, since 2×211212221² = 89221204599505682, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 211212196 and 211212205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211212241) 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, 15755 + ... + 25896.

It is an arithmetic number, because the mean of its divisors is an integer number (28864836).

Almost surely, 2^211212221 is an apocalyptic number.

It is an amenable number.

211212221 is a deficient number, since it is larger than the sum of its proper divisors (19706467).

211212221 is a wasteful number, since it uses less digits than its factorization.

211212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42123.

The product of its digits is 32, while the sum is 14.

The square root of 211212221 is about 14533.1421585286. The cubic root of 211212221 is about 595.5337075084.

Adding to 211212221 its reverse (122212112), we get a palindrome (333424333).

The spelling of 211212221 in words is "two hundred eleven million, two hundred twelve thousand, two hundred twenty-one".