821317686 has 16 divisors (see below), whose sum is σ = 1877297664. Its totient is φ = 234662184.

The previous prime is 821317681. The next prime is 821317771. The reversal of 821317686 is 686713128.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 19555183 = 821317686 / (8 + 2 + 1 + 3 + 1 + 7 + 6 + 8 + 6).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821317681) 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 in 7 ways as a sum of consecutive naturals, for example, 9777550 + ... + 9777633.

It is an arithmetic number, because the mean of its divisors is an integer number (117331104).

Almost surely, 2^821317686 is an apocalyptic number.

821317686 is an abundant number, since it is smaller than the sum of its proper divisors (1055979978).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821317686 is a wasteful number, since it uses less digits than its factorization.

821317686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19555195.

The product of its digits is 96768, while the sum is 42.

The square root of 821317686 is about 28658.6406865364. The cubic root of 821317686 is about 936.4912521879.

The spelling of 821317686 in words is "eight hundred twenty-one million, three hundred seventeen thousand, six hundred eighty-six".