400021100 has 72 divisors (see below), whose sum is σ = 890443008. Its totient is φ = 155937600.

The previous prime is 400021081. The next prime is 400021147. The reversal of 400021100 is 1120004.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 731027 + ... + 731573.

It is an arithmetic number, because the mean of its divisors is an integer number (12367264).

Almost surely, 2^400021100 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 400021100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (445221504).

400021100 is an abundant number, since it is smaller than the sum of its proper divisors (490421908).

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

400021100 is a wasteful number, since it uses less digits than its factorization.

400021100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 735 (or 728 counting only the distinct ones).

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

The square root of 400021100 is about 20000.5274930438. The cubic root of 400021100 is about 736.8192550111.

Adding to 400021100 its reverse (1120004), we get a palindrome (401141104).

The spelling of 400021100 in words is "four hundred million, twenty-one thousand, one hundred".