999923021 has 4 divisors (see below), whose sum is σ = 1005910752. Its totient is φ = 993935292.

The previous prime is 999922981. The next prime is 999923027. The reversal of 999923021 is 120329999.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-999923021 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 (999923027) 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, 2993615 + ... + 2993948.

It is an arithmetic number, because the mean of its divisors is an integer number (251477688).

Almost surely, 2^999923021 is an apocalyptic number.

It is an amenable number.

999923021 is a deficient number, since it is larger than the sum of its proper divisors (5987731).

999923021 is a wasteful number, since it uses less digits than its factorization.

999923021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5987730.

The product of its (nonzero) digits is 78732, while the sum is 44.

The square root of 999923021 is about 31621.5594333992. The cubic root of 999923021 is about 999.9743396749.

The spelling of 999923021 in words is "nine hundred ninety-nine million, nine hundred twenty-three thousand, twenty-one".