111565661 has 4 divisors (see below), whose sum is σ = 111597024. Its totient is φ = 111534300.

The previous prime is 111565627. The next prime is 111565667. The reversal of 111565661 is 166565111.

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 an emirpimes, since its reverse is a distinct semiprime: 166565111 = 103 ⋅1617137.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-111565661 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 (111565667) 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, 9545 + ... + 17726.

It is an arithmetic number, because the mean of its divisors is an integer number (27899256).

Almost surely, 2^111565661 is an apocalyptic number.

It is an amenable number.

111565661 is a deficient number, since it is larger than the sum of its proper divisors (31363).

111565661 is an equidigital number, since it uses as much as digits as its factorization.

111565661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31362.

The product of its digits is 5400, while the sum is 32.

The square root of 111565661 is about 10562.4647218346. The cubic root of 111565661 is about 481.4045392035.

It can be divided in two parts, 11 and 1565661, that multiplied together give a palindrome (17222271).

The spelling of 111565661 in words is "one hundred eleven million, five hundred sixty-five thousand, six hundred sixty-one".