20640672 has 144 divisors (see below), whose sum is σ = 65356200. Its totient is φ = 6137856.

The previous prime is 20640667. The next prime is 20640679. The reversal of 20640672 is 27604602.

It can be written as a sum of positive squares in 4 ways, for example, as 14470416 + 6170256 = 3804^2 + 2484^2 .

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-3 number, since 3×20640672³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (20640679) 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 23 ways as a sum of consecutive naturals, for example, 138454 + ... + 138602.

Almost surely, 2^20640672 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 20640672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32678100).

20640672 is an abundant number, since it is smaller than the sum of its proper divisors (44715528).

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

20640672 is a wasteful number, since it uses less digits than its factorization.

20640672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215 (or 204 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 20640672 is about 4543.2006339144. The cubic root of 20640672 is about 274.3097709555.

It can be divided in two parts, 20640 and 672, that added together give a palindrome (21312).

The spelling of 20640672 in words is "twenty million, six hundred forty thousand, six hundred seventy-two".