400020400 has 120 divisors (see below), whose sum is σ = 1059637040. Its totient is φ = 144184320.

The previous prime is 400020391. The next prime is 400020407. The reversal of 400020400 is 4020004.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (400020407) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 222706 + ... + 224494.

Almost surely, 2^400020400 is an apocalyptic number.

400020400 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 400020400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (529818520).

400020400 is an abundant number, since it is smaller than the sum of its proper divisors (659616640).

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

400020400 is a wasteful number, since it uses less digits than its factorization.

400020400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1863 (or 1852 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 10.

The square root of 400020400 is about 20000.5099934977. The cubic root of 400020400 is about 736.8188252222.

400020400 divided by its sum of digits (10) gives a triangular number (40002040 = T₈₉₄₄).

Adding to 400020400 its reverse (4020004), we get a palindrome (404040404).

The spelling of 400020400 in words is "four hundred million, twenty thousand, four hundred".