20896640 has 64 divisors (see below), whose sum is σ = 50600160. Its totient is φ = 8251392.

The previous prime is 20896609. The next prime is 20896643. The reversal of 20896640 is 4669802.

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

It is a self number, because there is not a number n which added to its sum of digits gives 20896640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20896643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65762 + ... + 66078.

Almost surely, 2^20896640 is an apocalyptic number.

20896640 is a gapful number since it is divisible by the number (20) 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 20896640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25300080).

20896640 is an abundant number, since it is smaller than the sum of its proper divisors (29703520).

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

20896640 is a wasteful number, since it uses less digits than its factorization.

20896640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 439 (or 427 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 20896640 is about 4571.2842834372. The cubic root of 20896640 is about 275.4390342512.

The spelling of 20896640 in words is "twenty million, eight hundred ninety-six thousand, six hundred forty".