1665421305605 has 8 divisors (see below), whose sum is σ = 2022583947552. Its totient is φ = 1316284790608.

The previous prime is 1665421305599. The next prime is 1665421305619. The reversal of 1665421305605 is 5065031245661.

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 1665421305605 - 2⁸ = 1665421305349 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2006531279 + ... + 2006532108.

It is an arithmetic number, because the mean of its divisors is an integer number (252822993444).

Almost surely, 2^{1665421305605} is an apocalyptic number.

It is an amenable number.

1665421305605 is a deficient number, since it is larger than the sum of its proper divisors (357162641947).

1665421305605 is an equidigital number, since it uses as much as digits as its factorization.

1665421305605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4013063475.

The product of its (nonzero) digits is 648000, while the sum is 44.

The spelling of 1665421305605 in words is "one trillion, six hundred sixty-five billion, four hundred twenty-one million, three hundred five thousand, six hundred five".