20665408 has 56 divisors (see below), whose sum is σ = 43525440. Its totient is φ = 9715200.

The previous prime is 20665367. The next prime is 20665433. The reversal of 20665408 is 80456602.

It is a self number, because there is not a number n which added to its sum of digits gives 20665408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 148603 + ... + 148741.

It is an arithmetic number, because the mean of its divisors is an integer number (777240).

Almost surely, 2^20665408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20665408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21762720).

20665408 is an abundant number, since it is smaller than the sum of its proper divisors (22860032).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20665408 is a wasteful number, since it uses less digits than its factorization.

20665408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275 (or 265 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 31.

The square root of 20665408 is about 4545.9221286775. The cubic root of 20665408 is about 274.4193057898.

The spelling of 20665408 in words is "twenty million, six hundred sixty-five thousand, four hundred eight".