1166601055661 has 4 divisors (see below), whose sum is σ = 1206828678300. Its totient is φ = 1126373433024.

The previous prime is 1166601055589. The next prime is 1166601055681. The reversal of 1166601055661 is 1665501066611.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 281249908900 + 885351146761 = 530330^2 + 940931^2 .

It is a cyclic number.

It is not a de Polignac number, because 1166601055661 - 2¹⁰ = 1166601054637 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 (1166601055681) 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, 20113811276 + ... + 20113811333.

It is an arithmetic number, because the mean of its divisors is an integer number (301707169575).

Almost surely, 2^{1166601055661} is an apocalyptic number.

It is an amenable number.

1166601055661 is a deficient number, since it is larger than the sum of its proper divisors (40227622639).

1166601055661 is an equidigital number, since it uses as much as digits as its factorization.

1166601055661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40227622638.

The product of its (nonzero) digits is 194400, while the sum is 44.

The spelling of 1166601055661 in words is "one trillion, one hundred sixty-six billion, six hundred one million, fifty-five thousand, six hundred sixty-one".