20664539 has 8 divisors (see below), whose sum is σ = 23669760. Its totient is φ = 17672616.

The previous prime is 20664529. The next prime is 20664587. The reversal of 20664539 is 93546602.

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 20664539 - 2¹⁶ = 20599003 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20664499 and 20664508.

It is not an unprimeable number, because it can be changed into a prime (20664509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 272 + ... + 6434.

It is an arithmetic number, because the mean of its divisors is an integer number (2958720).

Almost surely, 2^20664539 is an apocalyptic number.

20664539 is a deficient number, since it is larger than the sum of its proper divisors (3005221).

20664539 is an equidigital number, since it uses as much as digits as its factorization.

20664539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6649.

The product of its (nonzero) digits is 38880, while the sum is 35.

The square root of 20664539 is about 4545.8265475049. The cubic root of 20664539 is about 274.4154592052.

The spelling of 20664539 in words is "twenty million, six hundred sixty-four thousand, five hundred thirty-nine".