821287345 has 8 divisors (see below), whose sum is σ = 985735080. Its totient is φ = 656903040.

The previous prime is 821287307. The next prime is 821287351. The reversal of 821287345 is 543782128.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 484528144 + 336759201 = 22012^2 + 18351^2 .

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

It is not a de Polignac number, because 821287345 - 2⁹ = 821286833 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 821287298 and 821287307.

It is an unprimeable number.

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, 20011 + ... + 45199.

It is an arithmetic number, because the mean of its divisors is an integer number (123216885).

Almost surely, 2^821287345 is an apocalyptic number.

It is an amenable number.

821287345 is a deficient number, since it is larger than the sum of its proper divisors (164447735).

821287345 is a wasteful number, since it uses less digits than its factorization.

821287345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31715.

The product of its digits is 107520, while the sum is 40.

The square root of 821287345 is about 28658.1113299533. Note that the first 3 decimals coincide. The cubic root of 821287345 is about 936.4797201374.

The spelling of 821287345 in words is "eight hundred twenty-one million, two hundred eighty-seven thousand, three hundred forty-five".