6645380878 has 4 divisors (see below), whose sum is σ = 9968071320. Its totient is φ = 3322690438.

The previous prime is 6645380849. The next prime is 6645380879. The reversal of 6645380878 is 8780835466.

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

It is a super-2 number, since 2×6645380878² = 88322174027376101768, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6645380879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1661345218 + ... + 1661345221.

It is an arithmetic number, because the mean of its divisors is an integer number (2492017830).

Almost surely, 2^6645380878 is an apocalyptic number.

6645380878 is a deficient number, since it is larger than the sum of its proper divisors (3322690442).

6645380878 is a wasteful number, since it uses less digits than its factorization.

6645380878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3322690441.

The product of its (nonzero) digits is 7741440, while the sum is 55.

The square root of 6645380878 is about 81519.2055775815. The cubic root of 6645380878 is about 1880.0668527230.

The spelling of 6645380878 in words is "six billion, six hundred forty-five million, three hundred eighty thousand, eight hundred seventy-eight".