821217265 has 8 divisors (see below), whose sum is σ = 1075048128. Its totient is φ = 597248880.

The previous prime is 821217263. The next prime is 821217269. The reversal of 821217265 is 562712128.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 821217265 - 2¹ = 821217263 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 821217265.

It is not an unprimeable number, because it can be changed into a prime (821217263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7465557 + ... + 7465666.

It is an arithmetic number, because the mean of its divisors is an integer number (134381016).

Almost surely, 2^821217265 is an apocalyptic number.

It is an amenable number.

821217265 is a deficient number, since it is larger than the sum of its proper divisors (253830863).

821217265 is a wasteful number, since it uses less digits than its factorization.

821217265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14931239.

The product of its digits is 13440, while the sum is 34.

The square root of 821217265 is about 28656.8886133858. Note that the first 3 decimals coincide. The cubic root of 821217265 is about 936.4530829457.

The spelling of 821217265 in words is "eight hundred twenty-one million, two hundred seventeen thousand, two hundred sixty-five".