11991487 has 4 divisors (see below), whose sum is σ = 12512880. Its totient is φ = 11470096.

The previous prime is 11991481. The next prime is 11991517. The reversal of 11991487 is 78419911.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 11991487 - 2¹⁹ = 11467199 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 (11991481) 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, 260662 + ... + 260707.

It is an arithmetic number, because the mean of its divisors is an integer number (3128220).

Almost surely, 2^11991487 is an apocalyptic number.

11991487 is a deficient number, since it is larger than the sum of its proper divisors (521393).

11991487 is an equidigital number, since it uses as much as digits as its factorization.

11991487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521392.

The product of its digits is 18144, while the sum is 40.

The square root of 11991487 is about 3462.8726514268. The cubic root of 11991487 is about 228.8886970792. Note that the first 3 decimals are identical.

The spelling of 11991487 in words is "eleven million, nine hundred ninety-one thousand, four hundred eighty-seven".