999017021 has 4 divisors (see below), whose sum is σ = 999850044. Its totient is φ = 998184000.

The previous prime is 999017009. The next prime is 999017051. The reversal of 999017021 is 120710999.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120710999 = 17 ⋅7100647.

It can be written as a sum of positive squares in 2 ways, for example, as 453093796 + 545923225 = 21286^2 + 23365^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-999017021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999017051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 414710 + ... + 417111.

It is an arithmetic number, because the mean of its divisors is an integer number (249962511).

Almost surely, 2^999017021 is an apocalyptic number.

It is an amenable number.

999017021 is a deficient number, since it is larger than the sum of its proper divisors (833023).

999017021 is a wasteful number, since it uses less digits than its factorization.

999017021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 833022.

The product of its (nonzero) digits is 10206, while the sum is 38.

The square root of 999017021 is about 31607.2305177154. The cubic root of 999017021 is about 999.6722329138.

The spelling of 999017021 in words is "nine hundred ninety-nine million, seventeen thousand, twenty-one".