400018 has 4 divisors (see below), whose sum is σ = 600030. Its totient is φ = 200008.

The previous prime is 400009. The next prime is 400031. The reversal of 400018 is 810004.

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

It can be written as a sum of positive squares in only one way, i.e., 393129 + 6889 = 627^2 + 83^2 .

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

400018 is a modest number, since divided by 18 gives 4 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 399980 and 400007.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100003 + ... + 100006.

2⁴⁰⁰⁰¹⁸ is an apocalyptic number.

400018 is a deficient number, since it is larger than the sum of its proper divisors (200012).

400018 is a wasteful number, since it uses less digits than its factorization.

400018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200011.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 400018 is about 632.4697621231. The cubic root of 400018 is about 73.6817351657.

The spelling of 400018 in words is "four hundred thousand, eighteen".