6721440 has 192 divisors, whose sum is σ = 24675840. Its totient is φ = 1520640.

The previous prime is 6721439. The next prime is 6721447. The reversal of 6721440 is 441276.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 6721440.

It is not an unprimeable number, because it can be changed into a prime (6721447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 100287 + ... + 100353.

It is an arithmetic number, because the mean of its divisors is an integer number (128520).

Almost surely, 2^6721440 is an apocalyptic number.

6721440 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 6721440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12337920).

6721440 is an abundant number, since it is smaller than the sum of its proper divisors (17954400).

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

6721440 is a wasteful number, since it uses less digits than its factorization.

6721440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115 (or 107 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 6721440 is about 2592.5740105154. The cubic root of 6721440 is about 188.7212373756.

It can be divided in two parts, 672 and 1440, that added together give a palindrome (2112).

The spelling of 6721440 in words is "six million, seven hundred twenty-one thousand, four hundred forty".