20684664 has 288 divisors, whose sum is σ = 78427440. Its totient is φ = 4838400.

The previous prime is 20684663. The next prime is 20684669. The reversal of 20684664 is 46648602.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20684663) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 504484 + ... + 504524.

Almost surely, 2^20684664 is an apocalyptic number.

20684664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20684664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39213720).

20684664 is an abundant number, since it is smaller than the sum of its proper divisors (57742776).

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

20684664 is a wasteful number, since it uses less digits than its factorization.

20684664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 77 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 20684664 is about 4548.0395776642. The cubic root of 20684664 is about 274.5045138458.

The spelling of 20684664 in words is "twenty million, six hundred eighty-four thousand, six hundred sixty-four".