20736640 has 32 divisors (see below), whose sum is σ = 49575060. Its totient is φ = 8294400.

The previous prime is 20736623. The next prime is 20736647. The reversal of 20736640 is 4663702.

It can be written as a sum of positive squares in 2 ways, for example, as 18731584 + 2005056 = 4328^2 + 1416^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a junction number, because it is equal to n+sod(n) for n = 20736599 and 20736608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20736647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15561 + ... + 16840.

Almost surely, 2^20736640 is an apocalyptic number.

20736640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20736640 is an abundant number, since it is smaller than the sum of its proper divisors (28838420).

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

20736640 is an equidigital number, since it uses as much as digits as its factorization.

20736640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32420 (or 32408 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 28.

The square root of 20736640 is about 4553.7501029371. The cubic root of 20736640 is about 274.7342446386.

The spelling of 20736640 in words is "twenty million, seven hundred thirty-six thousand, six hundred forty".