381691 has 4 divisors (see below), whose sum is σ = 401800. Its totient is φ = 361584.

The previous prime is 381673. The next prime is 381697. The reversal of 381691 is 196183.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196183 = 13 ⋅15091.

It is a cyclic number.

It is not a de Polignac number, because 381691 - 2⁵ = 381659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (381697) 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 3 ways as a sum of consecutive naturals, for example, 10026 + ... + 10063.

It is an arithmetic number, because the mean of its divisors is an integer number (100450).

2³⁸¹⁶⁹¹ is an apocalyptic number.

381691 is a deficient number, since it is larger than the sum of its proper divisors (20109).

381691 is a wasteful number, since it uses less digits than its factorization.

381691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20108.

The product of its digits is 1296, while the sum is 28.

The square root of 381691 is about 617.8114599131. The cubic root of 381691 is about 72.5388456116.

The spelling of 381691 in words is "three hundred eighty-one thousand, six hundred ninety-one".