9991257 has 8 divisors (see below), whose sum is σ = 14105376. Its totient is φ = 6268992.

The previous prime is 9991211. The next prime is 9991259. The reversal of 9991257 is 7521999.

9991257 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 9991257 - 2²² = 5796953 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (9991259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 97903 + ... + 98004.

It is an arithmetic number, because the mean of its divisors is an integer number (1763172).

Almost surely, 2^9991257 is an apocalyptic number.

It is an amenable number.

9991257 is a deficient number, since it is larger than the sum of its proper divisors (4114119).

9991257 is a wasteful number, since it uses less digits than its factorization.

9991257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195927.

The product of its digits is 51030, while the sum is 42.

The square root of 9991257 is about 3160.8949682013. The cubic root of 9991257 is about 215.3806632876.

The spelling of 9991257 in words is "nine million, nine hundred ninety-one thousand, two hundred fifty-seven".