6621640 has 16 divisors (see below), whose sum is σ = 14898780. Its totient is φ = 2648640.

The previous prime is 6621607. The next prime is 6621649. The reversal of 6621640 is 461266.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 5885476 + 736164 = 2426^2 + 858^2 .

It is a super-2 number, since 2×6621640² = 87692232579200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (6621649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82731 + ... + 82810.

Almost surely, 2^6621640 is an apocalyptic number.

It is an amenable number.

6621640 is an abundant number, since it is smaller than the sum of its proper divisors (8277140).

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

6621640 is a wasteful number, since it uses less digits than its factorization.

6621640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165552 (or 165548 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 6621640 is about 2573.2547483683. The cubic root of 6621640 is about 187.7825310962.

The spelling of 6621640 in words is "six million, six hundred twenty-one thousand, six hundred forty".