20517120 has 216 divisors, whose sum is σ = 77005656. Its totient is φ = 5013504.

The previous prime is 20517109. The next prime is 20517121. The reversal of 20517120 is 2171502.

It can be written as a sum of positive squares in 4 ways, for example, as 589824 + 19927296 = 768^2 + 4464^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20517093 and 20517102.

It is not an unprimeable number, because it can be changed into a prime (20517121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 149692 + ... + 149828.

Almost surely, 2^20517120 is an apocalyptic number.

20517120 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 20517120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38502828).

20517120 is an abundant number, since it is smaller than the sum of its proper divisors (56488536).

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

20517120 is a wasteful number, since it uses less digits than its factorization.

20517120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 160 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 20517120 is about 4529.5827622420. The cubic root of 20517120 is about 273.7613493762.

Adding to 20517120 its reverse (2171502), we get a palindrome (22688622).

The spelling of 20517120 in words is "twenty million, five hundred seventeen thousand, one hundred twenty".