6661560660991 has 8 divisors (see below), whose sum is σ = 7022855526624. Its totient is φ = 6306237611520.

The previous prime is 6661560660959. The next prime is 6661560661001. The reversal of 6661560660991 is 1990660651666.

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 6661560660991 - 2⁵ = 6661560660959 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 (6661560660901) 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, 1492951750 + ... + 1492956211.

It is an arithmetic number, because the mean of its divisors is an integer number (877856940828).

Almost surely, 2^{6661560660991} is an apocalyptic number.

6661560660991 is a deficient number, since it is larger than the sum of its proper divisors (361294865633).

6661560660991 is a wasteful number, since it uses less digits than its factorization.

6661560660991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2985908081.

The product of its (nonzero) digits is 18895680, while the sum is 61.

The spelling of 6661560660991 in words is "six trillion, six hundred sixty-one billion, five hundred sixty million, six hundred sixty thousand, nine hundred ninety-one".