20990823 has 8 divisors (see below), whose sum is σ = 31986048. Its totient is φ = 11994744.

The previous prime is 20990821. The next prime is 20990831. The reversal of 20990823 is 32809902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20990823 - 2¹ = 20990821 is a prime.

It is a super-2 number, since 2×20990823² = 881229300434658, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20990821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 499761 + ... + 499802.

It is an arithmetic number, because the mean of its divisors is an integer number (3998256).

Almost surely, 2^20990823 is an apocalyptic number.

20990823 is a deficient number, since it is larger than the sum of its proper divisors (10995225).

20990823 is an equidigital number, since it uses as much as digits as its factorization.

20990823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 999573.

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 20990823 is about 4581.5742927513. The cubic root of 20990823 is about 275.8522234538.

The spelling of 20990823 in words is "twenty million, nine hundred ninety thousand, eight hundred twenty-three".