20255640 has 128 divisors (see below), whose sum is σ = 65318400. Its totient is φ = 5012480.

The previous prime is 20255639. The next prime is 20255647. The reversal of 20255640 is 4655202.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20255640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20255647) by changing a digit.

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, 113071 + ... + 113249.

It is an arithmetic number, because the mean of its divisors is an integer number (510300).

Almost surely, 2^20255640 is an apocalyptic number.

20255640 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 20255640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32659200).

20255640 is an abundant number, since it is smaller than the sum of its proper divisors (45062760).

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

20255640 is a wasteful number, since it uses less digits than its factorization.

20255640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257 (or 253 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 20255640 is about 4500.6266230382. The cubic root of 20255640 is about 272.5933916626.

The spelling of 20255640 in words is "twenty million, two hundred fifty-five thousand, six hundred forty".