999021021 has 16 divisors (see below), whose sum is σ = 1365027840. Its totient is φ = 649560240.

The previous prime is 999021019. The next prime is 999021041. The reversal of 999021021 is 120120999.

It is not a de Polignac number, because 999021021 - 2¹ = 999021019 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999021041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87366 + ... + 98136.

It is an arithmetic number, because the mean of its divisors is an integer number (85314240).

Almost surely, 2^999021021 is an apocalyptic number.

It is an amenable number.

999021021 is a deficient number, since it is larger than the sum of its proper divisors (366006819).

999021021 is a wasteful number, since it uses less digits than its factorization.

999021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11536.

The product of its (nonzero) digits is 2916, while the sum is 33.

The square root of 999021021 is about 31607.2937943127. The cubic root of 999021021 is about 999.6735671198.

The spelling of 999021021 in words is "nine hundred ninety-nine million, twenty-one thousand, twenty-one".