400390 has 8 divisors (see below), whose sum is σ = 720720. Its totient is φ = 160152.

The previous prime is 400381. The next prime is 400391. The reversal of 400390 is 93004.

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

It is a super-4 number, since 4×400390⁴ (a number of 24 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400391) by changing a digit.

400390 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 (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20010 + ... + 20029.

It is an arithmetic number, because the mean of its divisors is an integer number (90090).

2⁴⁰⁰³⁹⁰ is an apocalyptic number.

400390 is a deficient number, since it is larger than the sum of its proper divisors (320330).

400390 is a wasteful number, since it uses less digits than its factorization.

400390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40046.

The product of its (nonzero) digits is 108, while the sum is 16.

The square root of 400390 is about 632.7637789887. The cubic root of 400390 is about 73.7045683992.

Adding to 400390 its reverse (93004), we get a palindrome (493394).

The spelling of 400390 in words is "four hundred thousand, three hundred ninety".