20517220 has 48 divisors (see below), whose sum is σ = 44706816. Its totient is φ = 7904000.

The previous prime is 20517199. The next prime is 20517221. The reversal of 20517220 is 2271502.

It is not an unprimeable number, because it can be changed into a prime (20517221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 107325 + ... + 107515.

It is an arithmetic number, because the mean of its divisors is an integer number (931392).

Almost surely, 2^20517220 is an apocalyptic number.

20517220 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 20517220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22353408).

20517220 is an abundant number, since it is smaller than the sum of its proper divisors (24189596).

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

20517220 is a wasteful number, since it uses less digits than its factorization.

20517220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372 (or 370 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 20517220 is about 4529.5938007729. The cubic root of 20517220 is about 273.7617941445.

Adding to 20517220 its reverse (2271502), we get a palindrome (22788722).

The spelling of 20517220 in words is "twenty million, five hundred seventeen thousand, two hundred twenty".