11991515 has 16 divisors (see below), whose sum is σ = 15069888. Its totient is φ = 9150336.

The previous prime is 11991481. The next prime is 11991517. The reversal of 11991515 is 51519911.

11991515 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 11991515 - 2¹² = 11987419 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11991517) 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 15 ways as a sum of consecutive naturals, for example, 9194 + ... + 10416.

It is an arithmetic number, because the mean of its divisors is an integer number (941868).

Almost surely, 2^11991515 is an apocalyptic number.

11991515 is a deficient number, since it is larger than the sum of its proper divisors (3078373).

11991515 is a wasteful number, since it uses less digits than its factorization.

11991515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1318.

The product of its digits is 2025, while the sum is 32.

The square root of 11991515 is about 3462.8766943107. The cubic root of 11991515 is about 228.8888752300. Note that the first 4 decimals are identical.

The spelling of 11991515 in words is "eleven million, nine hundred ninety-one thousand, five hundred fifteen".