388639 has 4 divisors (see below), whose sum is σ = 398160. Its totient is φ = 379120.

The previous prime is 388621. The next prime is 388651. The reversal of 388639 is 936883.

388639 = 252² + 253² + ... + 257².

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 936883 = 113 ⋅8291.

It is a cyclic number.

It is not a de Polignac number, because 388639 - 2¹³ = 380447 is a prime.

It is a Duffinian number.

388639 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 388598 and 388607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (388699) by changing a digit.

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, 4699 + ... + 4780.

It is an arithmetic number, because the mean of its divisors is an integer number (99540).

2³⁸⁸⁶³⁹ is an apocalyptic number.

388639 is a deficient number, since it is larger than the sum of its proper divisors (9521).

388639 is an equidigital number, since it uses as much as digits as its factorization.

388639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9520.

The product of its digits is 31104, while the sum is 37.

The square root of 388639 is about 623.4091754217. The cubic root of 388639 is about 72.9763481267.

The spelling of 388639 in words is "three hundred eighty-eight thousand, six hundred thirty-nine".