7561991657 has 16 divisors (see below), whose sum is σ = 8537443200. Its totient is φ = 6634736640.

The previous prime is 7561991641. The next prime is 7561991677.

7561991657 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 7561991657 - 2⁴ = 7561991641 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7561991677) 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 15 ways as a sum of consecutive naturals, for example, 1365428 + ... + 1370954.

It is an arithmetic number, because the mean of its divisors is an integer number (533590200).

Almost surely, 2^7561991657 is an apocalyptic number.

It is an amenable number.

7561991657 is a deficient number, since it is larger than the sum of its proper divisors (975451543).

7561991657 is a wasteful number, since it uses less digits than its factorization.

7561991657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9856.

The product of its digits is 3572100, while the sum is 56.

The square root of 7561991657 is about 86959.7128387623. The cubic root of 7561991657 is about 1962.8121213008.

The spelling of 7561991657 in words is "seven billion, five hundred sixty-one million, nine hundred ninety-one thousand, six hundred fifty-seven".