111611161551661 has 4 divisors (see below), whose sum is σ = 112463155151424. Its totient is φ = 110759167951900.

The previous prime is 111611161551629. The next prime is 111611161551691. The reversal of 111611161551661 is 166155161116111.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 111611161551661 - 2⁵ = 111611161551629 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 (111611161551691) 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, 425996799685 + ... + 425996799946.

It is an arithmetic number, because the mean of its divisors is an integer number (28115788787856).

Almost surely, 2^{111611161551661} is an apocalyptic number.

It is an amenable number.

111611161551661 is a deficient number, since it is larger than the sum of its proper divisors (851993599763).

111611161551661 is an equidigital number, since it uses as much as digits as its factorization.

111611161551661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851993599762.

The product of its digits is 32400, while the sum is 43.

The spelling of 111611161551661 in words is "one hundred eleven trillion, six hundred eleven billion, one hundred sixty-one million, five hundred fifty-one thousand, six hundred sixty-one".