2165794006561 has 4 divisors (see below), whose sum is σ = 2259958963392. Its totient is φ = 2071629049732.

The previous prime is 2165794006559. The next prime is 2165794006601. The reversal of 2165794006561 is 1656004975612.

It is a happy number.

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 2165794006561 - 2¹ = 2165794006559 is a prime.

It is a super-2 number, since 2×2165794006561² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2165794006499 and 2165794006508.

It is not an unprimeable number, because it can be changed into a prime (2165794046561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47082478381 + ... + 47082478426.

It is an arithmetic number, because the mean of its divisors is an integer number (564989740848).

Almost surely, 2^{2165794006561} is an apocalyptic number.

It is an amenable number.

2165794006561 is a deficient number, since it is larger than the sum of its proper divisors (94164956831).

2165794006561 is an equidigital number, since it uses as much as digits as its factorization.

2165794006561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94164956830.

The product of its (nonzero) digits is 2721600, while the sum is 52.

The spelling of 2165794006561 in words is "two trillion, one hundred sixty-five billion, seven hundred ninety-four million, six thousand, five hundred sixty-one".