20724040 has 16 divisors (see below), whose sum is σ = 46629180. Its totient is φ = 8289600.

The previous prime is 20724019. The next prime is 20724047. The reversal of 20724040 is 4042702.

It can be written as a sum of positive squares in 2 ways, for example, as 19695844 + 1028196 = 4438^2 + 1014^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20723999 and 20724017.

It is not an unprimeable number, because it can be changed into a prime (20724047) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 259011 + ... + 259090.

Almost surely, 2^20724040 is an apocalyptic number.

20724040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20724040 is an abundant number, since it is smaller than the sum of its proper divisors (25905140).

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

20724040 is a wasteful number, since it uses less digits than its factorization.

20724040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 518112 (or 518108 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 19.

The square root of 20724040 is about 4552.3664175899. The cubic root of 20724040 is about 274.6785886783.

Adding to 20724040 its reverse (4042702), we get a palindrome (24766742).

The spelling of 20724040 in words is "twenty million, seven hundred twenty-four thousand, forty".