12111661 has 4 divisors (see below), whose sum is σ = 12121312. Its totient is φ = 12102012.

The previous prime is 12111601. The next prime is 12111707. The reversal of 12111661 is 16611121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16611121 = 353 ⋅47057.

It is a cyclic number.

It is not a de Polignac number, because 12111661 - 2⁹ = 12111149 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 (12111601) 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, 2601 + ... + 5566.

It is an arithmetic number, because the mean of its divisors is an integer number (3030328).

Almost surely, 2^12111661 is an apocalyptic number.

It is an amenable number.

12111661 is a deficient number, since it is larger than the sum of its proper divisors (9651).

12111661 is an equidigital number, since it uses as much as digits as its factorization.

12111661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9650.

The product of its digits is 72, while the sum is 19.

The square root of 12111661 is about 3480.1811734449. The cubic root of 12111661 is about 229.6507680413.

Adding to 12111661 its reverse (16611121), we get a palindrome (28722782).

The spelling of 12111661 in words is "twelve million, one hundred eleven thousand, six hundred sixty-one".