16821265 has 4 divisors (see below), whose sum is σ = 20185524. Its totient is φ = 13457008.

The previous prime is 16821227. The next prime is 16821269. The reversal of 16821265 is 56212861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56212861 = 929 ⋅60509.

It can be written as a sum of positive squares in 2 ways, for example, as 11209104 + 5612161 = 3348^2 + 2369^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16821265 is a prime.

It is a super-3 number, since 3×16821265³ (a number of 23 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16821269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1682122 + ... + 1682131.

It is an arithmetic number, because the mean of its divisors is an integer number (5046381).

Almost surely, 2^16821265 is an apocalyptic number.

It is an amenable number.

16821265 is a deficient number, since it is larger than the sum of its proper divisors (3364259).

16821265 is an equidigital number, since it uses as much as digits as its factorization.

16821265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3364258.

The product of its digits is 5760, while the sum is 31.

The square root of 16821265 is about 4101.3735504097. The cubic root of 16821265 is about 256.2238490069.

The spelling of 16821265 in words is "sixteen million, eight hundred twenty-one thousand, two hundred sixty-five".