21002217 has 4 divisors (see below), whose sum is σ = 28002960. Its totient is φ = 14001476.

The previous prime is 21002213. The next prime is 21002231. The reversal of 21002217 is 71220012.

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 21002217 - 2² = 21002213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21002196 and 21002205.

It is not an unprimeable number, because it can be changed into a prime (21002213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3500367 + ... + 3500372.

It is an arithmetic number, because the mean of its divisors is an integer number (7000740).

Almost surely, 2^21002217 is an apocalyptic number.

It is an amenable number.

21002217 is a deficient number, since it is larger than the sum of its proper divisors (7000743).

21002217 is an equidigital number, since it uses as much as digits as its factorization.

21002217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7000742.

The product of its (nonzero) digits is 56, while the sum is 15.

The square root of 21002217 is about 4582.8175831032. The cubic root of 21002217 is about 275.9021260820.

Adding to 21002217 its reverse (71220012), we get a palindrome (92222229).

The spelling of 21002217 in words is "twenty-one million, two thousand, two hundred seventeen".