21217201 has 4 divisors (see below), whose sum is σ = 22139712. Its totient is φ = 20294692.

The previous prime is 21217199. The next prime is 21217223. The reversal of 21217201 is 10271212.

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 21217201 - 2¹ = 21217199 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21217271) 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, 461221 + ... + 461266.

It is an arithmetic number, because the mean of its divisors is an integer number (5534928).

Almost surely, 2^21217201 is an apocalyptic number.

It is an amenable number.

21217201 is a deficient number, since it is larger than the sum of its proper divisors (922511).

21217201 is an equidigital number, since it uses as much as digits as its factorization.

21217201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922510.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 21217201 is about 4606.2133037887. The cubic root of 21217201 is about 276.8403333769.

Adding to 21217201 its reverse (10271212), we get a palindrome (31488413).

The spelling of 21217201 in words is "twenty-one million, two hundred seventeen thousand, two hundred one".