2123378865 has 12 divisors (see below), whose sum is σ = 3680523444. Its totient is φ = 1132468704.

The previous prime is 2123378857. The next prime is 2123378867. The reversal of 2123378865 is 5688733212.

2123378865 is a `hidden beast` number, since 212 + 3 + 378 + 8 + 65 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 398721024 + 1724657841 = 19968^2 + 41529^2 .

It is not a de Polignac number, because 2123378865 - 2³ = 2123378857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 47186197 = 2123378865 / (2 + 1 + 2 + 3 + 3 + 7 + 8 + 8 + 6 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 2123378865.

It is not an unprimeable number, because it can be changed into a prime (2123378867) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 23593054 + ... + 23593143.

It is an arithmetic number, because the mean of its divisors is an integer number (306710287).

Almost surely, 2^2123378865 is an apocalyptic number.

It is an amenable number.

2123378865 is a deficient number, since it is larger than the sum of its proper divisors (1557144579).

2123378865 is a wasteful number, since it uses less digits than its factorization.

2123378865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47186208 (or 47186205 counting only the distinct ones).

The product of its digits is 483840, while the sum is 45.

The square root of 2123378865 is about 46080.1352537078. The cubic root of 2123378865 is about 1285.3137792479.

The spelling of 2123378865 in words is "two billion, one hundred twenty-three million, three hundred seventy-eight thousand, eight hundred sixty-five".