939991 has 4 divisors (see below), whose sum is σ = 1012312. Its totient is φ = 867672.

The previous prime is 939989. The next prime is 939997. The reversal of 939991 is 199939.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199939 = 23 ⋅8693.

It is not a de Polignac number, because 939991 - 2¹ = 939989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (939997) 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, 36141 + ... + 36166.

It is an arithmetic number, because the mean of its divisors is an integer number (253078).

2⁹³⁹⁹⁹¹ is an apocalyptic number.

939991 is a deficient number, since it is larger than the sum of its proper divisors (72321).

939991 is a wasteful number, since it uses less digits than its factorization.

939991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72320.

The product of its digits is 19683, while the sum is 40.

The square root of 939991 is about 969.5313300765. The cubic root of 939991 is about 97.9582982367.

It can be divided in two parts, 9 and 39991, that added together give a square (40000 = 200²).

The spelling of 939991 in words is "nine hundred thirty-nine thousand, nine hundred ninety-one".