20823509 has 8 divisors (see below), whose sum is σ = 24188928. Its totient is φ = 17555760.

The previous prime is 20823497. The next prime is 20823553. The reversal of 20823509 is 90532802.

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

It is a cyclic number.

It is not a de Polignac number, because 20823509 - 2⁴ = 20823493 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20823109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23957 + ... + 24810.

It is an arithmetic number, because the mean of its divisors is an integer number (3023616).

Almost surely, 2^20823509 is an apocalyptic number.

It is an amenable number.

20823509 is a deficient number, since it is larger than the sum of its proper divisors (3365419).

20823509 is an equidigital number, since it uses as much as digits as its factorization.

20823509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48835.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 20823509 is about 4563.2783171751. The cubic root of 20823509 is about 275.1173449621.

The spelling of 20823509 in words is "twenty million, eight hundred twenty-three thousand, five hundred nine".