111601561 has 4 divisors (see below), whose sum is σ = 111965392. Its totient is φ = 111237732.

The previous prime is 111601531. The next prime is 111601577. The reversal of 111601561 is 165106111.

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: 165106111 = 43 ⋅3839677.

It is a cyclic number.

It is not a de Polignac number, because 111601561 - 2¹¹ = 111599513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (111601531) 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, 181455 + ... + 182068.

It is an arithmetic number, because the mean of its divisors is an integer number (27991348).

Almost surely, 2^111601561 is an apocalyptic number.

It is an amenable number.

111601561 is a deficient number, since it is larger than the sum of its proper divisors (363831).

111601561 is an equidigital number, since it uses as much as digits as its factorization.

111601561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363830.

The product of its (nonzero) digits is 180, while the sum is 22.

The square root of 111601561 is about 10564.1639991057. The cubic root of 111601561 is about 481.4561696945.

Adding to 111601561 its reverse (165106111), we get a palindrome (276707672).

It can be divided in two parts, 11160 and 1561, that added together give a palindrome (12721).

The spelling of 111601561 in words is "one hundred eleven million, six hundred one thousand, five hundred sixty-one".