999999623 has 4 divisors (see below), whose sum is σ = 1142856720. Its totient is φ = 857142528.

The previous prime is 999999613. The next prime is 999999667. The reversal of 999999623 is 326999999.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 999999623 - 2⁴ = 999999607 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 999999623.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999999613) 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, 71428538 + ... + 71428551.

It is an arithmetic number, because the mean of its divisors is an integer number (285714180).

Almost surely, 2^999999623 is an apocalyptic number.

999999623 is a deficient number, since it is larger than the sum of its proper divisors (142857097).

999999623 is a wasteful number, since it uses less digits than its factorization.

999999623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142857096.

The product of its digits is 19131876, while the sum is 65.

The square root of 999999623 is about 31622.7706407898. The cubic root of 999999623 is about 999.9998743333. Note that the first 3 decimals are identical.

The spelling of 999999623 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, six hundred twenty-three".