8656516621 has 2 divisors, whose sum is σ = 8656516622. Its totient is φ = 8656516620.

The previous prime is 8656516613. The next prime is 8656516667. The reversal of 8656516621 is 1266156568.

8656516621 = 65789² + 65790².

It is an a-pointer prime, because the next prime (8656516667) can be obtained adding 8656516621 to its sum of digits (46).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4328324100 + 4328192521 = 65790^2 + 65789^2 .

It is a cyclic number.

It is not a de Polignac number, because 8656516621 - 2³ = 8656516613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8656516021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4328258310 + 4328258311.

It is an arithmetic number, because the mean of its divisors is an integer number (4328258311).

Almost surely, 2^8656516621 is an apocalyptic number.

8656516621 is the 65790-th centered square number.

It is an amenable number.

8656516621 is a deficient number, since it is larger than the sum of its proper divisors (1).

8656516621 is an equidigital number, since it uses as much as digits as its factorization.

8656516621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 518400, while the sum is 46.

The square root of 8656516621 is about 93040.4031644317. The cubic root of 8656516621 is about 2053.2778511431.

The spelling of 8656516621 in words is "eight billion, six hundred fifty-six million, five hundred sixteen thousand, six hundred twenty-one".