20530640 has 80 divisors (see below), whose sum is σ = 54163200. Its totient is φ = 7174656.

The previous prime is 20530619. The next prime is 20530669. The reversal of 20530640 is 4603502.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 19241 + ... + 20279.

It is an arithmetic number, because the mean of its divisors is an integer number (677040).

Almost surely, 2^20530640 is an apocalyptic number.

20530640 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 20530640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27081600).

20530640 is an abundant number, since it is smaller than the sum of its proper divisors (33632560).

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

20530640 is a wasteful number, since it uses less digits than its factorization.

20530640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1084 (or 1078 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 20530640 is about 4531.0749276524. The cubic root of 20530640 is about 273.8214689373.

The spelling of 20530640 in words is "twenty million, five hundred thirty thousand, six hundred forty".