821582220717 has 12 divisors (see below), whose sum is σ = 1186745355900. Its totient is φ = 547714335168.

The previous prime is 821582220659. The next prime is 821582220721. The reversal of 821582220717 is 717022285128.

It can be written as a sum of positive squares in 2 ways, for example, as 449904221001 + 371677999716 = 670749^2 + 609654^2 .

It is not a de Polignac number, because 821582220717 - 2²⁷ = 821448002989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821582220787) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 186873 + ... + 1295409.

It is an arithmetic number, because the mean of its divisors is an integer number (98895446325).

Almost surely, 2^821582220717 is an apocalyptic number.

It is an amenable number.

821582220717 is a deficient number, since it is larger than the sum of its proper divisors (365163135183).

821582220717 is a wasteful number, since it uses less digits than its factorization.

821582220717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1190892 (or 1190889 counting only the distinct ones).

The product of its (nonzero) digits is 250880, while the sum is 45.

The spelling of 821582220717 in words is "eight hundred twenty-one billion, five hundred eighty-two million, two hundred twenty thousand, seven hundred seventeen".