9557991 has 12 divisors (see below), whose sum is σ = 13832832. Its totient is φ = 6359616.

The previous prime is 9557987. The next prime is 9557993. The reversal of 9557991 is 1997559.

9557991 is a `hidden beast` number, since 9 + 557 + 9 + 91 = 666.

It is not a de Polignac number, because 9557991 - 2² = 9557987 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9557993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8250 + ... + 9336.

It is an arithmetic number, because the mean of its divisors is an integer number (1152736).

Almost surely, 2^9557991 is an apocalyptic number.

9557991 is a deficient number, since it is larger than the sum of its proper divisors (4274841).

9557991 is a wasteful number, since it uses less digits than its factorization.

9557991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2070 (or 2067 counting only the distinct ones).

The product of its digits is 127575, while the sum is 45.

The square root of 9557991 is about 3091.6000711606. The cubic root of 9557991 is about 212.2212520425.

The spelling of 9557991 in words is "nine million, five hundred fifty-seven thousand, nine hundred ninety-one".