20281240 has 64 divisors (see below), whose sum is σ = 52695360. Its totient is φ = 6881280.

The previous prime is 20281229. The next prime is 20281241. The reversal of 20281240 is 4218202.

It is a super-2 number, since 2×20281240² = 822657391875200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20281241) 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, 31320 + ... + 31960.

It is an arithmetic number, because the mean of its divisors is an integer number (823365).

Almost surely, 2^20281240 is an apocalyptic number.

20281240 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 20281240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26347680).

20281240 is an abundant number, since it is smaller than the sum of its proper divisors (32414120).

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

20281240 is a wasteful number, since it uses less digits than its factorization.

20281240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 772 (or 768 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 20281240 is about 4503.4697734081. The cubic root of 20281240 is about 272.7081819634.

Adding to 20281240 its reverse (4218202), we get a palindrome (24499442).

The spelling of 20281240 in words is "twenty million, two hundred eighty-one thousand, two hundred forty".