2165819651 has 4 divisors (see below), whose sum is σ = 2171626512. Its totient is φ = 2160012792.

The previous prime is 2165819647. The next prime is 2165819653. The reversal of 2165819651 is 1569185612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2165819651 - 2² = 2165819647 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2165819653) 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, 2902871 + ... + 2903616.

It is an arithmetic number, because the mean of its divisors is an integer number (542906628).

Almost surely, 2^2165819651 is an apocalyptic number.

2165819651 is a deficient number, since it is larger than the sum of its proper divisors (5806861).

2165819651 is an equidigital number, since it uses as much as digits as its factorization.

2165819651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5806860.

The product of its digits is 129600, while the sum is 44.

The square root of 2165819651 is about 46538.3675154168. The cubic root of 2165819651 is about 1293.8207042473.

The spelling of 2165819651 in words is "two billion, one hundred sixty-five million, eight hundred nineteen thousand, six hundred fifty-one".