1661111161 has 8 divisors (see below), whose sum is σ = 1715360000. Its totient is φ = 1606903920.

The previous prime is 1661111093. The next prime is 1661111173. The reversal of 1661111161 is 1611111661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1661111161 - 2¹⁷ = 1660980089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661115161) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 84715 + ... + 102463.

It is an arithmetic number, because the mean of its divisors is an integer number (214420000).

Almost surely, 2^1661111161 is an apocalyptic number.

It is an amenable number.

1661111161 is a deficient number, since it is larger than the sum of its proper divisors (54248839).

1661111161 is a wasteful number, since it uses less digits than its factorization.

1661111161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20799.

The product of its digits is 216, while the sum is 25.

The square root of 1661111161 is about 40756.7314808241. The cubic root of 1661111161 is about 1184.3122790037.

It can be divided in two parts, 16611 and 11161, that added together give a palindrome (27772).

The spelling of 1661111161 in words is "one billion, six hundred sixty-one million, one hundred eleven thousand, one hundred sixty-one".