20609664 has 64 divisors (see below), whose sum is σ = 55226880. Its totient is φ = 6809600.

The previous prime is 20609653. The next prime is 20609683. The reversal of 20609664 is 46690602.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73204 + ... + 73484.

It is an arithmetic number, because the mean of its divisors is an integer number (862920).

Almost surely, 2^20609664 is an apocalyptic number.

20609664 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 20609664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27613440).

20609664 is an abundant number, since it is smaller than the sum of its proper divisors (34617216).

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

20609664 is a wasteful number, since it uses less digits than its factorization.

20609664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 489 (or 477 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 20609664 is about 4539.7867791340. The cubic root of 20609664 is about 274.1723390558.

The spelling of 20609664 in words is "twenty million, six hundred nine thousand, six hundred sixty-four".