2161409665 has 8 divisors (see below), whose sum is σ = 2746261800. Its totient is φ = 1627414272.

The previous prime is 2161409651. The next prime is 2161409753. The reversal of 2161409665 is 5669041612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1093492624 + 1067917041 = 33068^2 + 32679^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2161409665 - 2¹⁷ = 2161278593 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12714090 + ... + 12714259.

It is an arithmetic number, because the mean of its divisors is an integer number (343282725).

Almost surely, 2^2161409665 is an apocalyptic number.

It is an amenable number.

2161409665 is a deficient number, since it is larger than the sum of its proper divisors (584852135).

2161409665 is a wasteful number, since it uses less digits than its factorization.

2161409665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25428371.

The product of its (nonzero) digits is 77760, while the sum is 40.

The square root of 2161409665 is about 46490.9632616921. The cubic root of 2161409665 is about 1292.9419594579.

The spelling of 2161409665 in words is "two billion, one hundred sixty-one million, four hundred nine thousand, six hundred sixty-five".