20664709 has 8 divisors (see below), whose sum is σ = 22370040. Its totient is φ = 18975936.

The previous prime is 20664689. The next prime is 20664727. The reversal of 20664709 is 90746602.

It can be written as a sum of positive squares in 4 ways, for example, as 459684 + 20205025 = 678^2 + 4495^2 .

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 20664709 - 2²¹ = 18567557 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 (20664409) 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, 1474 + ... + 6595.

It is an arithmetic number, because the mean of its divisors is an integer number (2796255).

Almost surely, 2^20664709 is an apocalyptic number.

It is an amenable number.

20664709 is a deficient number, since it is larger than the sum of its proper divisors (1705331).

20664709 is a wasteful number, since it uses less digits than its factorization.

20664709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8279.

The product of its (nonzero) digits is 18144, while the sum is 34.

The square root of 20664709 is about 4545.8452459361. The cubic root of 20664709 is about 274.4162117101.

The spelling of 20664709 in words is "twenty million, six hundred sixty-four thousand, seven hundred nine".