363991 has 4 divisors (see below), whose sum is σ = 366184. Its totient is φ = 361800.

The previous prime is 363989. The next prime is 364027. The reversal of 363991 is 199363.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199363 = 73 ⋅2731.

It is a cyclic number.

It is not a de Polignac number, because 363991 - 2¹ = 363989 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 (363901) 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, 825 + ... + 1186.

It is an arithmetic number, because the mean of its divisors is an integer number (91546).

2³⁶³⁹⁹¹ is an apocalyptic number.

363991 is a deficient number, since it is larger than the sum of its proper divisors (2193).

363991 is a wasteful number, since it uses less digits than its factorization.

363991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2192.

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

The square root of 363991 is about 603.3166664365. The cubic root of 363991 is about 71.3997813498.

The spelling of 363991 in words is "three hundred sixty-three thousand, nine hundred ninety-one".