1665654146561 has 4 divisors (see below), whose sum is σ = 1665658433712. Its totient is φ = 1665649859412.

The previous prime is 1665654146539. The next prime is 1665654146591. The reversal of 1665654146561 is 1656414565661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1665654146561 - 2³⁰ = 1664580404737 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1665654146497 and 1665654146506.

It is not an unprimeable number, because it can be changed into a prime (1665654146521) 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, 1495475 + ... + 2359608.

It is an arithmetic number, because the mean of its divisors is an integer number (416414608428).

Almost surely, 2^{1665654146561} is an apocalyptic number.

It is an amenable number.

1665654146561 is a deficient number, since it is larger than the sum of its proper divisors (4287151).

1665654146561 is an equidigital number, since it uses as much as digits as its factorization.

1665654146561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4287150.

The product of its digits is 15552000, while the sum is 56.

The spelling of 1665654146561 in words is "one trillion, six hundred sixty-five billion, six hundred fifty-four million, one hundred forty-six thousand, five hundred sixty-one".