6906640 has 80 divisors (see below), whose sum is σ = 17967600. Its totient is φ = 2451456.

The previous prime is 6906637. The next prime is 6906649. The reversal of 6906640 is 466096.

It can be written as a sum of positive squares in 8 ways, for example, as 256 + 6906384 = 16^2 + 2628^2 .

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

It is not an unprimeable number, because it can be changed into a prime (6906649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30046 + ... + 30274.

It is an arithmetic number, because the mean of its divisors is an integer number (224595).

Almost surely, 2^6906640 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 6906640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8983800).

6906640 is an abundant number, since it is smaller than the sum of its proper divisors (11060960).

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

6906640 is a wasteful number, since it uses less digits than its factorization.

6906640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284 (or 278 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 6906640 is about 2628.0487057891. The cubic root of 6906640 is about 190.4388746741.

The spelling of 6906640 in words is "six million, nine hundred six thousand, six hundred forty".