11111661 has 24 divisors (see below), whose sum is σ = 18162144. Its totient is φ = 6732720.

The previous prime is 11111651. The next prime is 11111677. The reversal of 11111661 is 16611111.

11111661 is a `hidden beast` number, since 1 + 1 + 1 + 1 + 1 + 661 = 666.

It is not a de Polignac number, because 11111661 - 2¹¹ = 11109613 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111621) 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 23 ways as a sum of consecutive naturals, for example, 595 + ... + 4751.

It is an arithmetic number, because the mean of its divisors is an integer number (756756).

Almost surely, 2^11111661 is an apocalyptic number.

11111661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11111661 is a deficient number, since it is larger than the sum of its proper divisors (7050483).

11111661 is an equidigital number, since it uses as much as digits as its factorization.

11111661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4183 (or 4171 counting only the distinct ones).

The product of its digits is 36, while the sum is 18.

The square root of 11111661 is about 3333.4158156462. The cubic root of 11111661 is about 223.1479977707.

Adding to 11111661 its reverse (16611111), we get a palindrome (27722772).

It can be divided in two parts, 1111 and 1661, that added together give a palindrome (2772).

The spelling of 11111661 in words is "eleven million, one hundred eleven thousand, six hundred sixty-one".