20205540 has 36 divisors (see below), whose sum is σ = 61290684. Its totient is φ = 5388096.

The previous prime is 20205533. The next prime is 20205541. The reversal of 20205540 is 4550202.

It can be written as a sum of positive squares in 2 ways, for example, as 4901796 + 15303744 = 2214^2 + 3912^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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

It is not an unprimeable number, because it can be changed into a prime (20205541) 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 11 ways as a sum of consecutive naturals, for example, 55947 + ... + 56306.

It is an arithmetic number, because the mean of its divisors is an integer number (1702519).

Almost surely, 2^20205540 is an apocalyptic number.

20205540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20205540 is an abundant number, since it is smaller than the sum of its proper divisors (41085144).

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

20205540 is a wasteful number, since it uses less digits than its factorization.

20205540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112268 (or 112263 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 18.

The square root of 20205540 is about 4495.0572855082. The cubic root of 20205540 is about 272.3684632964.

Adding to 20205540 its reverse (4550202), we get a palindrome (24755742).

The spelling of 20205540 in words is "twenty million, two hundred five thousand, five hundred forty".