2161378645 has 8 divisors (see below), whose sum is σ = 2593936440. Its totient is φ = 1728914880.

The previous prime is 2161378633. The next prime is 2161378669. The reversal of 2161378645 is 5468731612.

It can be written as a sum of positive squares in 4 ways, for example, as 645210801 + 1516167844 = 25401^2 + 38938^2 .

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

It is not a de Polignac number, because 2161378645 - 2¹⁷ = 2161247573 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45471 + ... + 79939.

It is an arithmetic number, because the mean of its divisors is an integer number (324242055).

Almost surely, 2^2161378645 is an apocalyptic number.

It is an amenable number.

2161378645 is a deficient number, since it is larger than the sum of its proper divisors (432557795).

2161378645 is a wasteful number, since it uses less digits than its factorization.

2161378645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47015.

The product of its digits is 241920, while the sum is 43.

The square root of 2161378645 is about 46490.6296472741. The cubic root of 2161378645 is about 1292.9357741039.

The spelling of 2161378645 in words is "two billion, one hundred sixty-one million, three hundred seventy-eight thousand, six hundred forty-five".