391728 has 20 divisors (see below), whose sum is σ = 1012088. Its totient is φ = 130560.

The previous prime is 391717. The next prime is 391733. The reversal of 391728 is 827193.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 391695 and 391704.

It is an unprimeable number.

391728 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4033 + ... + 4128.

2³⁹¹⁷²⁸ is an apocalyptic number.

It is an amenable number.

391728 is an abundant number, since it is smaller than the sum of its proper divisors (620360).

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

391728 is a wasteful number, since it uses less digits than its factorization.

391728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8172 (or 8166 counting only the distinct ones).

The product of its digits is 3024, while the sum is 30.

The square root of 391728 is about 625.8817779741. The cubic root of 391728 is about 73.1691828832.

The spelling of 391728 in words is "three hundred ninety-one thousand, seven hundred twenty-eight".