391289 has 4 divisors (see below), whose sum is σ = 414324. Its totient is φ = 368256.

The previous prime is 391283. The next prime is 391291. The reversal of 391289 is 982193.

391289 = T₂₀₆ + T₂₀₇ + ... + T₂₂₂.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 982193 = 421 ⋅2333.

It can be written as a sum of positive squares in 2 ways, for example, as 258064 + 133225 = 508^2 + 365^2 .

It is a cyclic number.

It is not a de Polignac number, because 391289 - 2⁴ = 391273 is a prime.

It is not an unprimeable number, because it can be changed into a prime (391283) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11492 + ... + 11525.

It is an arithmetic number, because the mean of its divisors is an integer number (103581).

2³⁹¹²⁸⁹ is an apocalyptic number.

It is an amenable number.

391289 is a deficient number, since it is larger than the sum of its proper divisors (23035).

391289 is a wasteful number, since it uses less digits than its factorization.

391289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23034.

The product of its digits is 3888, while the sum is 32.

The square root of 391289 is about 625.5309744529. The cubic root of 391289 is about 73.1418396944.

The spelling of 391289 in words is "three hundred ninety-one thousand, two hundred eighty-nine".