820656647705 has 4 divisors (see below), whose sum is σ = 984787977252. Its totient is φ = 656525318160.

The previous prime is 820656647693. The next prime is 820656647711. The reversal of 820656647705 is 507746656028.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 274411488649 + 546245159056 = 523843^2 + 739084^2 .

It is not a de Polignac number, because 820656647705 - 2¹⁴ = 820656631321 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82065664766 + ... + 82065664775.

It is an arithmetic number, because the mean of its divisors is an integer number (246196994313).

Almost surely, 2^820656647705 is an apocalyptic number.

It is an amenable number.

820656647705 is a deficient number, since it is larger than the sum of its proper divisors (164131329547).

820656647705 is a wasteful number, since it uses less digits than its factorization.

820656647705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164131329546.

The product of its (nonzero) digits is 16934400, while the sum is 56.

The spelling of 820656647705 in words is "eight hundred twenty billion, six hundred fifty-six million, six hundred forty-seven thousand, seven hundred five".