400638 has 16 divisors (see below), whose sum is σ = 915840. Its totient is φ = 114456.

The previous prime is 400619. The next prime is 400643. The reversal of 400638 is 836004.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

400638 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4728 + ... + 4811.

It is an arithmetic number, because the mean of its divisors is an integer number (57240).

2⁴⁰⁰⁶³⁸ is an apocalyptic number.

400638 is an abundant number, since it is smaller than the sum of its proper divisors (515202).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

400638 is a wasteful number, since it uses less digits than its factorization.

400638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9551.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 400638 is about 632.9597143579. The cubic root of 400638 is about 73.7197826989.

The spelling of 400638 in words is "four hundred thousand, six hundred thirty-eight".