21212201 has 8 divisors (see below), whose sum is σ = 22064064. Its totient is φ = 20376720.

The previous prime is 21212197. The next prime is 21212239. The reversal of 21212201 is 10221212.

It is a happy number.

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 21212201 - 2² = 21212197 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1421 + ... + 6666.

It is an arithmetic number, because the mean of its divisors is an integer number (2758008).

Almost surely, 2^21212201 is an apocalyptic number.

It is an amenable number.

21212201 is a deficient number, since it is larger than the sum of its proper divisors (851863).

21212201 is an equidigital number, since it uses as much as digits as its factorization.

21212201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8191.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21212201 is about 4605.6705266443. The cubic root of 21212201 is about 276.8185851357.

Adding to 21212201 its reverse (10221212), we get a palindrome (31433413).

The spelling of 21212201 in words is "twenty-one million, two hundred twelve thousand, two hundred one".