999990623 has 4 divisors (see below), whose sum is σ = 1005226368. Its totient is φ = 994754880.

The previous prime is 999990599. The next prime is 999990631. The reversal of 999990623 is 326099999.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 326099999 = 14341 ⋅22739.

It is a cyclic number.

It is not a de Polignac number, because 999990623 - 2¹⁸ = 999728479 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 (999990923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2617586 + ... + 2617967.

It is an arithmetic number, because the mean of its divisors is an integer number (251306592).

Almost surely, 2^999990623 is an apocalyptic number.

999990623 is a deficient number, since it is larger than the sum of its proper divisors (5235745).

999990623 is a wasteful number, since it uses less digits than its factorization.

999990623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5235744.

The product of its (nonzero) digits is 2125764, while the sum is 56.

The square root of 999990623 is about 31622.6283379481. The cubic root of 999990623 is about 999.9968743236.

The spelling of 999990623 in words is "nine hundred ninety-nine million, nine hundred ninety thousand, six hundred twenty-three".