400689 has 9 divisors (see below), whose sum is σ = 581529. Its totient is φ = 265860.

The previous prime is 400681. The next prime is 400703. The reversal of 400689 is 986004.

The square root of 400689 is 633.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 400689 - 2³ = 400681 is a prime.

It is an Ulam number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (400681) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1794 + ... + 2004.

2⁴⁰⁰⁶⁸⁹ is an apocalyptic number.

400689 is the 633-rd square number.

400689 is the 317-th centered octagonal number.

It is an amenable number.

400689 is a deficient number, since it is larger than the sum of its proper divisors (180840).

400689 is an equidigital number, since it uses as much as digits as its factorization.

400689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 428 (or 214 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The cubic root of 400689 is about 73.7229106676.

It can be divided in two parts, 4006 and 89, that added together give a triangular number (4095 = T₉₀).

The spelling of 400689 in words is "four hundred thousand, six hundred eighty-nine".