1665961027681 has 8 divisors (see below), whose sum is σ = 1730274134400. Its totient is φ = 1602105666000.

The previous prime is 1665961027673. The next prime is 1665961027793. The reversal of 1665961027681 is 1867201695661.

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 1665961027681 - 2³ = 1665961027673 is a prime.

It is a super-3 number, since 3×1665961027681³ (a number of 38 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665961027651) 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, 114428841 + ... + 114443398.

It is an arithmetic number, because the mean of its divisors is an integer number (216284266800).

Almost surely, 2^{1665961027681} is an apocalyptic number.

It is an amenable number.

1665961027681 is a deficient number, since it is larger than the sum of its proper divisors (64313106719).

1665961027681 is a wasteful number, since it uses less digits than its factorization.

1665961027681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228872519.

The product of its (nonzero) digits is 6531840, while the sum is 58.

The spelling of 1665961027681 in words is "one trillion, six hundred sixty-five billion, nine hundred sixty-one million, twenty-seven thousand, six hundred eighty-one".