11991863 has 4 divisors (see below), whose sum is σ = 12914328. Its totient is φ = 11069400.

The previous prime is 11991839. The next prime is 11991911. The reversal of 11991863 is 36819911.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 36819911 = 43 ⋅856277.

It is a cyclic number.

It is not a de Polignac number, because 11991863 - 2¹⁸ = 11729719 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11991263) 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 3 ways as a sum of consecutive naturals, for example, 461213 + ... + 461238.

It is an arithmetic number, because the mean of its divisors is an integer number (3228582).

Almost surely, 2^11991863 is an apocalyptic number.

11991863 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

11991863 is a deficient number, since it is larger than the sum of its proper divisors (922465).

11991863 is an equidigital number, since it uses as much as digits as its factorization.

11991863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922464.

The product of its digits is 11664, while the sum is 38.

The square root of 11991863 is about 3462.9269411872. The cubic root of 11991863 is about 228.8910893666.

The spelling of 11991863 in words is "eleven million, nine hundred ninety-one thousand, eight hundred sixty-three".