6781440 has 80 divisors (see below), whose sum is σ = 21703968. Its totient is φ = 1806336.

The previous prime is 6781433. The next prime is 6781457. The reversal of 6781440 is 441876.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 6781398 and 6781407.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7239 + ... + 8121.

Almost surely, 2^6781440 is an apocalyptic number.

6781440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6781440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10851984).

6781440 is an abundant number, since it is smaller than the sum of its proper divisors (14922528).

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

6781440 is an equidigital number, since it uses as much as digits as its factorization.

6781440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 909 (or 893 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 6781440 is about 2604.1198129118. The cubic root of 6781440 is about 189.2811247086.

The spelling of 6781440 in words is "six million, seven hundred eighty-one thousand, four hundred forty".