390820 has 12 divisors (see below), whose sum is σ = 820764. Its totient is φ = 156320.

The previous prime is 390809. The next prime is 390821. The reversal of 390820 is 28093.

It can be written as a sum of positive squares in 2 ways, for example, as 118336 + 272484 = 344^2 + 522^2 .

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 390791 and 390800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (390821) by changing a digit.

390820 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 (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9751 + ... + 9790.

It is an arithmetic number, because the mean of its divisors is an integer number (68397).

2³⁹⁰⁸²⁰ is an apocalyptic number.

It is an amenable number.

390820 is an abundant number, since it is smaller than the sum of its proper divisors (429944).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

390820 is a wasteful number, since it uses less digits than its factorization.

390820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19550 (or 19548 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 390820 is about 625.1559805361. The cubic root of 390820 is about 73.1126053456.

The spelling of 390820 in words is "three hundred ninety thousand, eight hundred twenty".