6690640 has 40 divisors (see below), whose sum is σ = 16972128. Its totient is φ = 2432640.

The previous prime is 6690623. The next prime is 6690643. The reversal of 6690640 is 460966.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6690643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2922 + ... + 4681.

Almost surely, 2^6690640 is an apocalyptic number.

It is an amenable number.

6690640 is an abundant number, since it is smaller than the sum of its proper divisors (10281488).

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

6690640 is a wasteful number, since it uses less digits than its factorization.

6690640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7627 (or 7621 counting only the distinct ones).

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

The square root of 6690640 is about 2586.6271474644. The cubic root of 6690640 is about 188.4325336027.

The spelling of 6690640 in words is "six million, six hundred ninety thousand, six hundred forty".