6991728 has 20 divisors (see below), whose sum is σ = 18062088. Its totient is φ = 2330560.

The previous prime is 6991723. The next prime is 6991729. The reversal of 6991728 is 8271996.

It is a zygodrome in base 7.

It is a self number, because there is not a number n which added to its sum of digits gives 6991728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6991723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72783 + ... + 72878.

Almost surely, 2^6991728 is an apocalyptic number.

It is an amenable number.

6991728 is an abundant number, since it is smaller than the sum of its proper divisors (11070360).

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

6991728 is a wasteful number, since it uses less digits than its factorization.

6991728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145672 (or 145666 counting only the distinct ones).

The product of its digits is 54432, while the sum is 42.

The square root of 6991728 is about 2644.1875878992. The cubic root of 6991728 is about 191.2177373063.

The spelling of 6991728 in words is "six million, nine hundred ninety-one thousand, seven hundred twenty-eight".