9656567721 has 6 divisors (see below), whose sum is σ = 13948375610. Its totient is φ = 6437711808.

The previous prime is 9656567693. The next prime is 9656567731. The reversal of 9656567721 is 1277656569.

9656567721 is a `hidden beast` number, since 9 + 6 + 5 + 6 + 567 + 72 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 8941593600 + 714974121 = 94560^2 + 26739^2 .

It is not a de Polignac number, because 9656567721 - 2⁷ = 9656567593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9656567731) 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 in 5 ways as a sum of consecutive naturals, for example, 536475976 + ... + 536475993.

Almost surely, 2^9656567721 is an apocalyptic number.

It is an amenable number.

9656567721 is a deficient number, since it is larger than the sum of its proper divisors (4291807889).

9656567721 is a wasteful number, since it uses less digits than its factorization.

9656567721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1072951975 (or 1072951972 counting only the distinct ones).

The product of its digits is 4762800, while the sum is 54.

The square root of 9656567721 is about 98267.8366557441. The cubic root of 9656567721 is about 2129.4834223038.

The spelling of 9656567721 in words is "nine billion, six hundred fifty-six million, five hundred sixty-seven thousand, seven hundred twenty-one".