9991001 has 4 divisors (see below), whose sum is σ = 10160400. Its totient is φ = 9821604.

The previous prime is 9990997. The next prime is 9991027. The reversal of 9991001 is 1001999.

9991001 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1001999 = 41 ⋅24439.

It is a cyclic number.

It is not a de Polignac number, because 9991001 - 2² = 9990997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9991301) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 84611 + ... + 84728.

It is an arithmetic number, because the mean of its divisors is an integer number (2540100).

Almost surely, 2^9991001 is an apocalyptic number.

It is an amenable number.

9991001 is a deficient number, since it is larger than the sum of its proper divisors (169399).

9991001 is a wasteful number, since it uses less digits than its factorization.

9991001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169398.

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 9991001 is about 3160.8544730816. The cubic root of 9991001 is about 215.3788237486.

It can be divided in two parts, 999 and 1001, that multiplied together give a palindrome (999999).

The spelling of 9991001 in words is "nine million, nine hundred ninety-one thousand, one".