1000400400 has 90 divisors (see below), whose sum is σ = 3471679770. Its totient is φ = 266772480.

The previous prime is 1000400381. The next prime is 1000400417. The reversal of 1000400400 is 40040001.

It can be written as a sum of positive squares in 3 ways, for example, as 99680256 + 900720144 = 9984^2 + 30012^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a Harshad number since it is a multiple of its sum of digits (9).

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 135345 + ... + 142544.

Almost surely, 2^1000400400 is an apocalyptic number.

1000400400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1000400400 is an abundant number, since it is smaller than the sum of its proper divisors (2471279370).

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

1000400400 is a wasteful number, since it uses less digits than its factorization.

1000400400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277913 (or 277899 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 1000400400 is about 31629.1068479652. The cubic root of 1000400400 is about 1000.1334488573.

Adding to 1000400400 its reverse (40040001), we get a palindrome (1040440401).

The spelling of 1000400400 in words is "one billion, four hundred thousand, four hundred".