993991 has 6 divisors (see below), whose sum is σ = 1039640. Its totient is φ = 950268.

The previous prime is 993983. The next prime is 993997. The reversal of 993991 is 199399.

It is not a de Polignac number, because 993991 - 2³ = 993983 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 (993997) 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, 411 + ... + 1468.

2⁹⁹³⁹⁹¹ is an apocalyptic number.

993991 is a deficient number, since it is larger than the sum of its proper divisors (45649).

993991 is a wasteful number, since it uses less digits than its factorization.

993991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1925 (or 1902 counting only the distinct ones).

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

The square root of 993991 is about 996.9909728779. The cubic root of 993991 is about 99.7992974544.

The spelling of 993991 in words is "nine hundred ninety-three thousand, nine hundred ninety-one".