378991 has 4 divisors (see below), whose sum is σ = 389272. Its totient is φ = 368712.

The previous prime is 378977. The next prime is 378997. The reversal of 378991 is 199873.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 378991 - 2¹⁵ = 346223 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 10243 = 378991 / (3 + 7 + 8 + 9 + 9 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 378991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (378997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5085 + ... + 5158.

It is an arithmetic number, because the mean of its divisors is an integer number (97318).

2³⁷⁸⁹⁹¹ is an apocalyptic number.

378991 is a deficient number, since it is larger than the sum of its proper divisors (10281).

378991 is a wasteful number, since it uses less digits than its factorization.

378991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10280.

The product of its digits is 13608, while the sum is 37.

The square root of 378991 is about 615.6224492333. The cubic root of 378991 is about 72.3673993209.

It can be divided in two parts, 378 and 991, that added together give a square (1369 = 37²).

The spelling of 378991 in words is "three hundred seventy-eight thousand, nine hundred ninety-one".