20281440 has 192 divisors, whose sum is σ = 69672960. Its totient is φ = 4945920.

The previous prime is 20281403. The next prime is 20281451. The reversal of 20281440 is 4418202.

It is a super-2 number, since 2×20281440² = 822673616947200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 431497 + ... + 431543.

It is an arithmetic number, because the mean of its divisors is an integer number (362880).

Almost surely, 2^20281440 is an apocalyptic number.

20281440 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 20281440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34836480).

20281440 is an abundant number, since it is smaller than the sum of its proper divisors (49391520).

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

20281440 is a wasteful number, since it uses less digits than its factorization.

20281440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 20281440 is about 4503.4919784541. The cubic root of 20281440 is about 272.7090783822.

Adding to 20281440 its reverse (4418202), we get a palindrome (24699642).

The spelling of 20281440 in words is "twenty million, two hundred eighty-one thousand, four hundred forty".