947991 has 16 divisors (see below), whose sum is σ = 1440000. Its totient is φ = 549120.

The previous prime is 947987. The next prime is 948007. The reversal of 947991 is 199749.

It is not a de Polignac number, because 947991 - 2² = 947987 is a prime.

947991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (947911) 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 15 ways as a sum of consecutive naturals, for example, 135 + ... + 1383.

It is an arithmetic number, because the mean of its divisors is an integer number (90000).

2⁹⁴⁷⁹⁹¹ is an apocalyptic number.

947991 is a deficient number, since it is larger than the sum of its proper divisors (492009).

947991 is a wasteful number, since it uses less digits than its factorization.

947991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1286.

The product of its digits is 20412, while the sum is 39.

The square root of 947991 is about 973.6482937899. The cubic root of 947991 is about 98.2354121133.

The spelling of 947991 in words is "nine hundred forty-seven thousand, nine hundred ninety-one".