400820 has 36 divisors (see below), whose sum is σ = 981540. Its totient is φ = 137088.

The previous prime is 400759. The next prime is 400823. The reversal of 400820 is 28004.

400820 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 268324 + 132496 = 518^2 + 364^2 .

It is a Harshad number since it is a multiple of its sum of digits (14).

400820 is a Rhonda number in base 8.

It is a nialpdrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 400795 and 400804.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 400820.

It is not an unprimeable number, because it can be changed into a prime (400823) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 776 + ... + 1184.

It is an arithmetic number, because the mean of its divisors is an integer number (27265).

2⁴⁰⁰⁸²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 400820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (490770).

400820 is an abundant number, since it is smaller than the sum of its proper divisors (580720).

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

400820 is a wasteful number, since it uses less digits than its factorization.

400820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432 (or 423 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 400820 is about 633.1034670573. The cubic root of 400820 is about 73.7309440377.

Adding to 400820 its reverse (28004), we get a palindrome (428824).

Subtracting from 400820 its reverse (28004), we obtain a triangular number (372816 = T₈₆₃).

The spelling of 400820 in words is "four hundred thousand, eight hundred twenty".