400003 has 4 divisors (see below), whose sum is σ = 401760. Its totient is φ = 398248.

The previous prime is 399989. The next prime is 400009. The reversal of 400003 is 300004.

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 400003 - 2⁹ = 399491 is a prime.

It is a Duffinian number.

400003 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (400009) 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, 475 + ... + 1012.

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

2⁴⁰⁰⁰⁰³ is an apocalyptic number.

400003 is a deficient number, since it is larger than the sum of its proper divisors (1757).

400003 is a wasteful number, since it uses less digits than its factorization.

400003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1756.

The product of its (nonzero) digits is 12, while the sum is 7.

The square root of 400003 is about 632.4579037375. The cubic root of 400003 is about 73.6808141739.

Adding to 400003 its reverse (300004), we get a palindrome (700007).

Subtracting from 400003 its reverse (300004), we obtain a palindrome (99999).

The spelling of 400003 in words is "four hundred thousand, three", and thus it is an iban number.