11997561 has 16 divisors (see below), whose sum is σ = 16646400. Its totient is φ = 7676928.

The previous prime is 11997553. The next prime is 11997577. The reversal of 11997561 is 16579911.

It is not a de Polignac number, because 11997561 - 2³ = 11997553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (11997551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20505 + ... + 21081.

It is an arithmetic number, because the mean of its divisors is an integer number (1040400).

Almost surely, 2^11997561 is an apocalyptic number.

It is an amenable number.

11997561 is a deficient number, since it is larger than the sum of its proper divisors (4648839).

11997561 is a wasteful number, since it uses less digits than its factorization.

11997561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 848.

The product of its digits is 17010, while the sum is 39.

The square root of 11997561 is about 3463.7495579213. The cubic root of 11997561 is about 228.9273365817.

The spelling of 11997561 in words is "eleven million, nine hundred ninety-seven thousand, five hundred sixty-one".