6440778 has 24 divisors (see below), whose sum is σ = 14040000. Its totient is φ = 2133864.

The previous prime is 6440771. The next prime is 6440779. The reversal of 6440778 is 8770446.

It is a happy number.

6440778 is a `hidden beast` number, since 644 + 0 + 7 + 7 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (6440771) 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, 2223 + ... + 4221.

It is an arithmetic number, because the mean of its divisors is an integer number (585000).

Almost surely, 2^6440778 is an apocalyptic number.

6440778 is an abundant number, since it is smaller than the sum of its proper divisors (7599222).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6440778 is a wasteful number, since it uses less digits than its factorization.

6440778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2186 (or 2183 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 36.

The square root of 6440778 is about 2537.8687909346. The cubic root of 6440778 is about 186.0570411247.

The spelling of 6440778 in words is "six million, four hundred forty thousand, seven hundred seventy-eight".