20205440 has 64 divisors (see below), whose sum is σ = 48874320. Its totient is φ = 7987200.

The previous prime is 20205389. The next prime is 20205467. The reversal of 20205440 is 4450202.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 83720 + ... + 83960.

Almost surely, 2^20205440 is an apocalyptic number.

20205440 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 20205440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24437160).

20205440 is an abundant number, since it is smaller than the sum of its proper divisors (28668880).

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

20205440 is a wasteful number, since it uses less digits than its factorization.

20205440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391 (or 379 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 17.

The square root of 20205440 is about 4495.0461621656. The cubic root of 20205440 is about 272.3680139660.

Adding to 20205440 its reverse (4450202), we get a palindrome (24655642).

The spelling of 20205440 in words is "twenty million, two hundred five thousand, four hundred forty".