11991001 has 8 divisors (see below), whose sum is σ = 13850784. Its totient is φ = 10259520.

The previous prime is 11990999. The next prime is 11991011. The reversal of 11991001 is 10019911.

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

It is a cyclic number.

It is not a de Polignac number, because 11991001 - 2¹ = 11990999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (11991011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31875 + ... + 32248.

It is an arithmetic number, because the mean of its divisors is an integer number (1731348).

Almost surely, 2^11991001 is an apocalyptic number.

11991001 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11991001 is a deficient number, since it is larger than the sum of its proper divisors (1859783).

11991001 is a wasteful number, since it uses less digits than its factorization.

11991001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64151.

The product of its (nonzero) digits is 81, while the sum is 22.

The square root of 11991001 is about 3462.8024777628. The cubic root of 11991001 is about 228.8856048464.

The spelling of 11991001 in words is "eleven million, nine hundred ninety-one thousand, one".