9891457691 has 2 divisors, whose sum is σ = 9891457692. Its totient is φ = 9891457690.

The previous prime is 9891457679. The next prime is 9891457753. The reversal of 9891457691 is 1967541989.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9891457691 - 2¹⁸ = 9891195547 is a prime.

It is a super-4 number, since 4×9891457691⁴ (a number of 41 digits) contains 4444 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 9891457691.

It is not a weakly prime, because it can be changed into another prime (9891457651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4945728845 + 4945728846.

It is an arithmetic number, because the mean of its divisors is an integer number (4945728846).

Almost surely, 2^9891457691 is an apocalyptic number.

9891457691 is a deficient number, since it is larger than the sum of its proper divisors (1).

9891457691 is an equidigital number, since it uses as much as digits as its factorization.

9891457691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4898880, while the sum is 59.

The square root of 9891457691 is about 99455.8077288602. The cubic root of 9891457691 is about 2146.6114056117.

The spelling of 9891457691 in words is "nine billion, eight hundred ninety-one million, four hundred fifty-seven thousand, six hundred ninety-one".