391966 has 8 divisors (see below), whose sum is σ = 613584. Its totient is φ = 187440.

The previous prime is 391961. The next prime is 391967. The reversal of 391966 is 669193.

391966 = T₁₇₃ + T₁₇₄ + ... + T₁₉₅.

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

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391961) by changing a digit.

391966 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 4215 + ... + 4306.

It is an arithmetic number, because the mean of its divisors is an integer number (76698).

2³⁹¹⁹⁶⁶ is an apocalyptic number.

391966 is a deficient number, since it is larger than the sum of its proper divisors (221618).

391966 is a wasteful number, since it uses less digits than its factorization.

391966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8546.

The product of its digits is 8748, while the sum is 34.

The square root of 391966 is about 626.0718808571. The cubic root of 391966 is about 73.1839982142.

The spelling of 391966 in words is "three hundred ninety-one thousand, nine hundred sixty-six".