999645 has 8 divisors (see below), whose sum is σ = 1599456. Its totient is φ = 533136.

The previous prime is 999631. The next prime is 999653. The reversal of 999645 is 546999.

It is a happy number.

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

It is not a de Polignac number, because 999645 - 2⁵ = 999613 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 999597 and 999606.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33307 + ... + 33336.

It is an arithmetic number, because the mean of its divisors is an integer number (199932).

2⁹⁹⁹⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

999645 is a deficient number, since it is larger than the sum of its proper divisors (599811).

999645 is a wasteful number, since it uses less digits than its factorization.

999645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66651.

The product of its digits is 87480, while the sum is 42.

The square root of 999645 is about 999.8224842441. The cubic root of 999645 is about 99.9881652661.

The spelling of 999645 in words is "nine hundred ninety-nine thousand, six hundred forty-five".