393691 has 4 divisors (see below), whose sum is σ = 410832. Its totient is φ = 376552.

The previous prime is 393683. The next prime is 393697. The reversal of 393691 is 196393.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196393 = 277 ⋅709.

It is a cyclic number.

It is not a de Polignac number, because 393691 - 2³ = 393683 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (393697) 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, 8536 + ... + 8581.

It is an arithmetic number, because the mean of its divisors is an integer number (102708).

2³⁹³⁶⁹¹ is an apocalyptic number.

393691 is a deficient number, since it is larger than the sum of its proper divisors (17141).

393691 is a wasteful number, since it uses less digits than its factorization.

393691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17140.

The product of its digits is 4374, while the sum is 31.

The square root of 393691 is about 627.4480058140. The cubic root of 393691 is about 73.2911993961.

The spelling of 393691 in words is "three hundred ninety-three thousand, six hundred ninety-one".