21022217 has 8 divisors (see below), whose sum is σ = 22802472. Its totient is φ = 19302400.

The previous prime is 21022213. The next prime is 21022219. The reversal of 21022217 is 71222012.

It can be written as a sum of positive squares in 4 ways, for example, as 3474496 + 17547721 = 1864^2 + 4189^2 .

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 21022217 - 2² = 21022213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21022195 and 21022204.

It is not an unprimeable number, because it can be changed into a prime (21022213) 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, 14384 + ... + 15777.

It is an arithmetic number, because the mean of its divisors is an integer number (2850309).

Almost surely, 2^21022217 is an apocalyptic number.

It is an amenable number.

21022217 is a deficient number, since it is larger than the sum of its proper divisors (1780255).

21022217 is a wasteful number, since it uses less digits than its factorization.

21022217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30219.

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 21022217 is about 4584.9991275899. Note that the first 3 decimals coincide. The cubic root of 21022217 is about 275.9896770276.

Adding to 21022217 its reverse (71222012), we get a palindrome (92244229).

The spelling of 21022217 in words is "twenty-one million, twenty-two thousand, two hundred seventeen".