2165526661 has 4 divisors (see below), whose sum is σ = 2167024672. Its totient is φ = 2164028652.

The previous prime is 2165526617. The next prime is 2165526673. The reversal of 2165526661 is 1666255612.

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 2165526661 - 2⁷ = 2165526533 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 (2165326661) 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, 746835 + ... + 749728.

It is an arithmetic number, because the mean of its divisors is an integer number (541756168).

Almost surely, 2^2165526661 is an apocalyptic number.

It is an amenable number.

2165526661 is a deficient number, since it is larger than the sum of its proper divisors (1498011).

2165526661 is a wasteful number, since it uses less digits than its factorization.

2165526661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1498010.

The product of its digits is 129600, while the sum is 40.

The square root of 2165526661 is about 46535.2195761447. The cubic root of 2165526661 is about 1293.7623593427.

The spelling of 2165526661 in words is "two billion, one hundred sixty-five million, five hundred twenty-six thousand, six hundred sixty-one".