991647 has 6 divisors (see below), whose sum is σ = 1432392. Its totient is φ = 661092.

The previous prime is 991643. The next prime is 991651. The reversal of 991647 is 746199.

991647 is a `hidden beast` number, since 9 + 9 + 1 + 647 = 666.

It is an interprime number because it is at equal distance from previous prime (991643) and next prime (991651).

It is not a de Polignac number, because 991647 - 2² = 991643 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991647.

It is not an unprimeable number, because it can be changed into a prime (991643) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 55083 + ... + 55100.

It is an arithmetic number, because the mean of its divisors is an integer number (238732).

2⁹⁹¹⁶⁴⁷ is an apocalyptic number.

991647 is a deficient number, since it is larger than the sum of its proper divisors (440745).

991647 is a wasteful number, since it uses less digits than its factorization.

991647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110189 (or 110186 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 991647 is about 995.8147418069. The cubic root of 991647 is about 99.7207877977.

The spelling of 991647 in words is "nine hundred ninety-one thousand, six hundred forty-seven".