400999 has 4 divisors (see below), whose sum is σ = 404064. Its totient is φ = 397936.

The previous prime is 400997. The next prime is 401017. The reversal of 400999 is 999004.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 400999 - 2¹ = 400997 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

400999 is a modest number, since divided by 999 gives 400 as remainder.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 400999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400997) by changing a digit.

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, 1327 + ... + 1600.

It is an arithmetic number, because the mean of its divisors is an integer number (101016).

2⁴⁰⁰⁹⁹⁹ is an apocalyptic number.

400999 is a deficient number, since it is larger than the sum of its proper divisors (3065).

400999 is a wasteful number, since it uses less digits than its factorization.

400999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3064.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 400999 is about 633.2448183760. The cubic root of 400999 is about 73.7419181032.

The spelling of 400999 in words is "four hundred thousand, nine hundred ninety-nine".