1661100665616 has 540 divisors, whose sum is σ = 5568698549232. Its totient is φ = 460778782464.

The previous prime is 1661100665611. The next prime is 1661100665663. The reversal of 1661100665616 is 6165660011661.

1661100665616 is a `hidden beast` number, since 16 + 6 + 1 + 10 + 0 + 6 + 6 + 5 + 616 = 666.

It is not an unprimeable number, because it can be changed into a prime (1661100665611) by changing a digit.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 2950444951 + ... + 2950445513.

Almost surely, 2^{1661100665616} is an apocalyptic number.

1661100665616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661100665616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2784349274616).

1661100665616 is an abundant number, since it is smaller than the sum of its proper divisors (3907597883616).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661100665616 is a wasteful number, since it uses less digits than its factorization.

1661100665616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816 (or 721 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The spelling of 1661100665616 in words is "one trillion, six hundred sixty-one billion, one hundred million, six hundred sixty-five thousand, six hundred sixteen".