900000001 has 4 divisors (see below), whose sum is σ = 902200900. Its totient is φ = 897799104.

The previous prime is 899999963. The next prime is 900000011. The reversal of 900000001 is 100000009.

It is a happy number.

It is a Cunningham number, because it is equal to 30000²+1.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 100000009 = 149 ⋅671141.

It can be written as a sum of positive squares in 2 ways, for example, as 822542400 + 77457601 = 28680^2 + 8801^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-900000001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (900000011) 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 3 ways as a sum of consecutive naturals, for example, 1099836 + ... + 1100653.

It is an arithmetic number, because the mean of its divisors is an integer number (225550225).

Almost surely, 2^900000001 is an apocalyptic number.

It is an amenable number.

900000001 is a deficient number, since it is larger than the sum of its proper divisors (2200899).

900000001 is a wasteful number, since it uses less digits than its factorization.

900000001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2200898.

The product of its (nonzero) digits is 9, while the sum is 10.

The square root of 900000001 is about 30000.0000166667. Note that the first 4 decimals coincide. The cubic root of 900000001 is about 965.4893849632.

The spelling of 900000001 in words is "nine hundred million, one", and thus it is an aban number.