16521217 has 2 divisors, whose sum is σ = 16521218. Its totient is φ = 16521216.

The previous prime is 16521209. The next prime is 16521221. The reversal of 16521217 is 71212561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16353936 + 167281 = 4044^2 + 409^2 .

It is a cyclic number.

It is not a de Polignac number, because 16521217 - 2³ = 16521209 is a prime.

It is a super-2 number, since 2×16521217² = 545901222322178, which contains 22 as substring.

It is equal to p_1062457 and since 16521217 and 1062457 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 16521191 and 16521200.

It is not a weakly prime, because it can be changed into another prime (16521227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8260608 + 8260609.

It is an arithmetic number, because the mean of its divisors is an integer number (8260609).

Almost surely, 2^16521217 is an apocalyptic number.

It is an amenable number.

16521217 is a deficient number, since it is larger than the sum of its proper divisors (1).

16521217 is an equidigital number, since it uses as much as digits as its factorization.

16521217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 840, while the sum is 25.

The square root of 16521217 is about 4064.6299954608. The cubic root of 16521217 is about 254.6912423478.

Adding to 16521217 its reverse (71212561), we get a palindrome (87733778).

The spelling of 16521217 in words is "sixteen million, five hundred twenty-one thousand, two hundred seventeen".