20724656 has 40 divisors (see below), whose sum is σ = 42259200. Its totient is φ = 9827136.

The previous prime is 20724653. The next prime is 20724659. The reversal of 20724656 is 65642702.

It is an interprime number because it is at equal distance from previous prime (20724653) and next prime (20724659).

It is a super-2 number, since 2×20724656² = 859022732636672, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20724653) 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, 73091 + ... + 73373.

It is an arithmetic number, because the mean of its divisors is an integer number (1056480).

Almost surely, 2^20724656 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 20724656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21129600).

20724656 is an abundant number, since it is smaller than the sum of its proper divisors (21534544).

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

20724656 is a wasteful number, since it uses less digits than its factorization.

20724656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 513 (or 507 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 32.

The square root of 20724656 is about 4552.4340742069. The cubic root of 20724656 is about 274.6813101607.

The spelling of 20724656 in words is "twenty million, seven hundred twenty-four thousand, six hundred fifty-six".