20281040 has 40 divisors (see below), whose sum is σ = 50783208. Its totient is φ = 7488000.

The previous prime is 20281039. The next prime is 20281043. The reversal of 20281040 is 4018202.

It can be written as a sum of positive squares in 4 ways, for example, as 425104 + 19855936 = 652^2 + 4456^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×20281040² = 822641166963200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20281043) 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, 8711 + ... + 10790.

Almost surely, 2^20281040 is an apocalyptic number.

20281040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20281040 is an abundant number, since it is smaller than the sum of its proper divisors (30502168).

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

20281040 is a wasteful number, since it uses less digits than its factorization.

20281040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19527 (or 19521 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 20281040 is about 4503.4475682526. The cubic root of 20281040 is about 272.7072855386.

Adding to 20281040 its reverse (4018202), we get a palindrome (24299242).

The spelling of 20281040 in words is "twenty million, two hundred eighty-one thousand, forty".