999000721 has 8 divisors (see below), whose sum is σ = 1020998888. Its totient is φ = 977184000.

The previous prime is 999000707. The next prime is 999000773. The reversal of 999000721 is 127000999.

999000721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 228161025 + 770839696 = 15105^2 + 27764^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 999000721 - 2¹³ = 998992529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (999000701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34200 + ... + 56281.

It is an arithmetic number, because the mean of its divisors is an integer number (127624861).

Almost surely, 2^999000721 is an apocalyptic number.

It is an amenable number.

999000721 is a deficient number, since it is larger than the sum of its proper divisors (21998167).

999000721 is a wasteful number, since it uses less digits than its factorization.

999000721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90723.

The product of its (nonzero) digits is 10206, while the sum is 37.

The square root of 999000721 is about 31606.9726642714. The cubic root of 999000721 is about 999.6667959874. Note that the first 3 decimals are identical.

The spelling of 999000721 in words is "nine hundred ninety-nine million, seven hundred twenty-one", and thus it is an aban number.