400401 has 12 divisors (see below), whose sum is σ = 612612. Its totient is φ = 251136.

The previous prime is 400391. The next prime is 400409. The reversal of 400401 is 104004.

It can be written as a sum of positive squares in 2 ways, for example, as 360000 + 40401 = 600^2 + 201^2 .

It is not a de Polignac number, because 400401 - 2¹¹ = 398353 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400409) 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 11 ways as a sum of consecutive naturals, for example, 1156 + ... + 1461.

It is an arithmetic number, because the mean of its divisors is an integer number (51051).

2⁴⁰⁰⁴⁰¹ is an apocalyptic number.

It is an amenable number.

400401 is a deficient number, since it is larger than the sum of its proper divisors (212211).

400401 is a wasteful number, since it uses less digits than its factorization.

400401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2640 (or 2637 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 400401 is about 632.7724709562. The cubic root of 400401 is about 73.7052433602.

Adding to 400401 its reverse (104004), we get a palindrome (504405).

The spelling of 400401 in words is "four hundred thousand, four hundred one", and thus it is an iban number.