1000000000 has 100 divisors (see below), whose sum is σ = 2497558338.
Its totient is φ = 400000000.
The previous prime is 999999937. The next prime is 1000000007. The reversal of 1000000000 is 1.
It is a happy number.
The cubic root of 1000000000 is 1000.
It is a perfect power (a cube, a 9-th power), and thus also a powerful number.
It can be written as a sum of positive squares in 5 ways, for example, as 940771584 + 59228416 = 30672^2 + 7696^2
It is a tau number, because it is divible by the number of its divisors (100).
It is a Harshad number since it is a multiple of its sum of digits (1).
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is a nialpdrome in base 10.
It is not an unprimeable number, because it can be changed into a prime (1000000007) by changing a digit.
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 9 ways as a sum of consecutive naturals, for example, 199999998 + ... + 200000002.
Almost surely, 21000000000 is an apocalyptic number.
1000000000 is a gapful number since it is divisible by the number (10) 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 1000000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1248779169).
1000000000 is an abundant number, since it is smaller than the sum of its proper divisors (1497558338).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1000000000 is an frugal number, since it uses more digits than its factorization.
1000000000 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 63 (or 7 counting only the distinct ones).
The product of its (nonzero) digits is 1, while the sum is 1.
The square root of 1000000000 is about 31622.7766016838.
The spelling of 1000000000 in words is "one billion", and thus it is an aban number and an uban number.