8656663621 has 2 divisors, whose sum is σ = 8656663622. Its totient is φ = 8656663620.

The previous prime is 8656663607. The next prime is 8656663643. The reversal of 8656663621 is 1263666568.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8540347396 + 116316225 = 92414^2 + 10785^2 .

It is a cyclic number.

It is not a de Polignac number, because 8656663621 - 2⁷ = 8656663493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8656663661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4328331810 + 4328331811.

It is an arithmetic number, because the mean of its divisors is an integer number (4328331811).

Almost surely, 2^8656663621 is an apocalyptic number.

It is an amenable number.

8656663621 is a deficient number, since it is larger than the sum of its proper divisors (1).

8656663621 is an equidigital number, since it uses as much as digits as its factorization.

8656663621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1866240, while the sum is 49.

The square root of 8656663621 is about 93041.1931404580. The cubic root of 8656663621 is about 2053.2894736062.

The spelling of 8656663621 in words is "eight billion, six hundred fifty-six million, six hundred sixty-three thousand, six hundred twenty-one".