2165546661 has 4 divisors (see below), whose sum is σ = 2887395552. Its totient is φ = 1443697772.

The previous prime is 2165546659. The next prime is 2165546681. The reversal of 2165546661 is 1666455612.

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 2165546661 - 2¹ = 2165546659 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2165546681) 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, 360924441 + ... + 360924446.

It is an arithmetic number, because the mean of its divisors is an integer number (721848888).

Almost surely, 2^2165546661 is an apocalyptic number.

It is an amenable number.

2165546661 is a deficient number, since it is larger than the sum of its proper divisors (721848891).

2165546661 is an equidigital number, since it uses as much as digits as its factorization.

2165546661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 721848890.

The product of its digits is 259200, while the sum is 42.

The square root of 2165546661 is about 46535.4344666513. The cubic root of 2165546661 is about 1293.7663422333.

The spelling of 2165546661 in words is "two billion, one hundred sixty-five million, five hundred forty-six thousand, six hundred sixty-one".