400001 has 4 divisors (see below), whose sum is σ = 457152. Its totient is φ = 342852.

The previous prime is 399989. The next prime is 400009. The reversal of 400001 is 100004.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 400001 - 2⁶ = 399937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (400009) by changing a digit.

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, 28565 + ... + 28578.

It is an arithmetic number, because the mean of its divisors is an integer number (114288).

2⁴⁰⁰⁰⁰¹ is an apocalyptic number.

It is an amenable number.

400001 is a deficient number, since it is larger than the sum of its proper divisors (57151).

400001 is an equidigital number, since it uses as much as digits as its factorization.

400001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57150.

The product of its (nonzero) digits is 4, while the sum is 5.

The square root of 400001 is about 632.4563226026. The cubic root of 400001 is about 73.6806913733.

Adding to 400001 its reverse (100004), we get a palindrome (500005).

The spelling of 400001 in words is "four hundred thousand, one", and thus it is an iban number.