400040000 has 140 divisors (see below), whose sum is σ = 1012897644. Its totient is φ = 156672000.

The previous prime is 400039999. The next prime is 400040021. The reversal of 400040000 is 40004.

Added to its reverse (40004) it gives a square (400080004 = 20002²).

It is a happy number.

It is a Cunningham number, because it is equal to 20001²-1.

It can be written as a sum of positive squares in 10 ways, for example, as 280093696 + 119946304 = 16736^2 + 10952^2 .

It is a Harshad number since it is a multiple of its sum of digits (8).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a self number, because there is not a number n which added to its sum of digits gives 400040000.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2919932 + ... + 2920068.

Almost surely, 2^400040000 is an apocalyptic number.

400040000 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 400040000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (506448822).

400040000 is an abundant number, since it is smaller than the sum of its proper divisors (612857644).

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

400040000 is an equidigital number, since it uses as much as digits as its factorization.

400040000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242 (or 217 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 8.

The square root of 400040000 is about 20000.9999750012. Note that the first 4 decimals coincide. The cubic root of 400040000 is about 736.8308591194.

Adding to 400040000 its reverse (40004), we get a palindrome (400080004).

Multiplying 400040000 by its reverse (40004), we get a square (16003200160000 = 4000400²).

400040000 divided by its reverse (40004) gives a 4-th power (10000 = 10⁴).

The spelling of 400040000 in words is "four hundred million, forty thousand".