6440778992 has 80 divisors (see below), whose sum is σ = 13356288000. Its totient is φ = 3000022272.

The previous prime is 6440778947. The next prime is 6440779019. The reversal of 6440778992 is 2998770446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8957609 + ... + 8958327.

It is an arithmetic number, because the mean of its divisors is an integer number (166953600).

Almost surely, 2^6440778992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6440778992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (6678144000).

6440778992 is an abundant number, since it is smaller than the sum of its proper divisors (6915509008).

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

6440778992 is a wasteful number, since it uses less digits than its factorization.

6440778992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1198 (or 1192 counting only the distinct ones).

The product of its (nonzero) digits is 6096384, while the sum is 56.

The square root of 6440778992 is about 80254.4640004530. The cubic root of 6440778992 is about 1860.5705067683.

The spelling of 6440778992 in words is "six billion, four hundred forty million, seven hundred seventy-eight thousand, nine hundred ninety-two".