20664599 has 4 divisors (see below), whose sum is σ = 20745264. Its totient is φ = 20583936.

The previous prime is 20664587. The next prime is 20664601. The reversal of 20664599 is 99546602.

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 20664599 - 2¹⁶ = 20599063 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 (20664509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39947 + ... + 40460.

It is an arithmetic number, because the mean of its divisors is an integer number (5186316).

Almost surely, 2^20664599 is an apocalyptic number.

20664599 is a deficient number, since it is larger than the sum of its proper divisors (80665).

20664599 is an equidigital number, since it uses as much as digits as its factorization.

20664599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80664.

The product of its (nonzero) digits is 116640, while the sum is 41.

The square root of 20664599 is about 4545.8331469600. The cubic root of 20664599 is about 274.4157247956.

The spelling of 20664599 in words is "twenty million, six hundred sixty-four thousand, five hundred ninety-nine".