400399 has 4 divisors (see below), whose sum is σ = 401760. Its totient is φ = 399040.

The previous prime is 400391. The next prime is 400409. The reversal of 400399 is 993004.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 400399 - 2³ = 400391 is a prime.

It is a super-3 number, since 3×400399³ = 192575133314163597, which contains 333 as substring.

It is a Duffinian number.

400399 is a lucky number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400391) 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, 34 + ... + 895.

It is an arithmetic number, because the mean of its divisors is an integer number (100440).

2⁴⁰⁰³⁹⁹ is an apocalyptic number.

400399 is a deficient number, since it is larger than the sum of its proper divisors (1361).

400399 is an equidigital number, since it uses as much as digits as its factorization.

400399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1360.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 400399 is about 632.7708906073. The cubic root of 400399 is about 73.7051206409.

The spelling of 400399 in words is "four hundred thousand, three hundred ninety-nine".