21352217 has 2 divisors, whose sum is σ = 21352218. Its totient is φ = 21352216.

The previous prime is 21352213. The next prime is 21352223. The reversal of 21352217 is 71225312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13756681 + 7595536 = 3709^2 + 2756^2 .

It is a cyclic number.

It is not a de Polignac number, because 21352217 - 2² = 21352213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21352192 and 21352201.

It is not a weakly prime, because it can be changed into another prime (21352213) 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 as a sum of consecutive naturals, namely, 10676108 + 10676109.

It is an arithmetic number, because the mean of its divisors is an integer number (10676109).

Almost surely, 2^21352217 is an apocalyptic number.

It is an amenable number.

21352217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21352217 is an equidigital number, since it uses as much as digits as its factorization.

21352217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 840, while the sum is 23.

The square root of 21352217 is about 4620.8459182275. The cubic root of 21352217 is about 277.4263181267.

Adding to 21352217 its reverse (71225312), we get a palindrome (92577529).

The spelling of 21352217 in words is "twenty-one million, three hundred fifty-two thousand, two hundred seventeen".