391969 has 4 divisors (see below), whose sum is σ = 415044. Its totient is φ = 368896.

The previous prime is 391967. The next prime is 391987. The reversal of 391969 is 969193.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 969193 = 59 ⋅16427.

It can be written as a sum of positive squares in 2 ways, for example, as 345744 + 46225 = 588^2 + 215^2 .

It is a cyclic number.

It is not a de Polignac number, because 391969 - 2¹ = 391967 is a prime.

It is a super-2 number, since 2×391969² = 307279393922, which contains 22 as substring.

It is a Duffinian number.

391969 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (391961) 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, 11512 + ... + 11545.

It is an arithmetic number, because the mean of its divisors is an integer number (103761).

2³⁹¹⁹⁶⁹ is an apocalyptic number.

It is an amenable number.

391969 is a deficient number, since it is larger than the sum of its proper divisors (23075).

391969 is a wasteful number, since it uses less digits than its factorization.

391969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23074.

The product of its digits is 13122, while the sum is 37.

The square root of 391969 is about 626.0742767436. The cubic root of 391969 is about 73.1841849238.

The spelling of 391969 in words is "three hundred ninety-one thousand, nine hundred sixty-nine".