391945 has 8 divisors (see below), whose sum is σ = 481536. Its totient is φ = 306096.

The previous prime is 391939. The next prime is 391961. The reversal of 391945 is 549193.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 391945 - 2⁷ = 391817 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 697 + ... + 1126.

It is an arithmetic number, because the mean of its divisors is an integer number (60192).

2³⁹¹⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

391945 is a deficient number, since it is larger than the sum of its proper divisors (89591).

391945 is a wasteful number, since it uses less digits than its factorization.

391945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1871.

The product of its digits is 4860, while the sum is 31.

The square root of 391945 is about 626.0551093953. The cubic root of 391945 is about 73.1826912204.

It can be divided in two parts, 39 and 1945, that multiplied together give a triangular number (75855 = T₃₈₉).

The spelling of 391945 in words is "three hundred ninety-one thousand, nine hundred forty-five".