21276217 has 4 divisors (see below), whose sum is σ = 21286800. Its totient is φ = 21265636.

The previous prime is 21276209. The next prime is 21276263. The reversal of 21276217 is 71267212.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21276217 - 2³ = 21276209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21276287) 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 3 ways as a sum of consecutive naturals, for example, 1243 + ... + 6640.

It is an arithmetic number, because the mean of its divisors is an integer number (5321700).

Almost surely, 2^21276217 is an apocalyptic number.

It is an amenable number.

21276217 is a deficient number, since it is larger than the sum of its proper divisors (10583).

21276217 is an equidigital number, since it uses as much as digits as its factorization.

21276217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10582.

The product of its digits is 2352, while the sum is 28.

The square root of 21276217 is about 4612.6149850166. The cubic root of 21276217 is about 277.0967744336.

The spelling of 21276217 in words is "twenty-one million, two hundred seventy-six thousand, two hundred seventeen".