20640239 has 8 divisors (see below), whose sum is σ = 21010080. Its totient is φ = 20272896.

The previous prime is 20640233. The next prime is 20640247. The reversal of 20640239 is 93204602.

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 20640239 - 2¹⁶ = 20574703 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 (20640233) 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, 24182 + ... + 25020.

It is an arithmetic number, because the mean of its divisors is an integer number (2626260).

Almost surely, 2^20640239 is an apocalyptic number.

20640239 is a deficient number, since it is larger than the sum of its proper divisors (369841).

20640239 is an equidigital number, since it uses as much as digits as its factorization.

20640239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1249.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 20640239 is about 4543.1529800349. The cubic root of 20640239 is about 274.3078527854.

The spelling of 20640239 in words is "twenty million, six hundred forty thousand, two hundred thirty-nine".