255644640 has 288 divisors, whose sum is σ = 963718560. Its totient is φ = 63074304.

The previous prime is 255644629. The next prime is 255644647. The reversal of 255644640 is 46446552.

255644640 is a `hidden beast` number, since 2 + 5 + 5 + 6 + 4 + 4 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 255644595 and 255644604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (255644647) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4332931 + ... + 4332989.

It is an arithmetic number, because the mean of its divisors is an integer number (3346245).

Almost surely, 2^255644640 is an apocalyptic number.

255644640 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 255644640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (481859280).

255644640 is an abundant number, since it is smaller than the sum of its proper divisors (708073920).

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

255644640 is a wasteful number, since it uses less digits than its factorization.

255644640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159 (or 86 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 36.

The square root of 255644640 is about 15988.8911435409. The cubic root of 255644640 is about 634.6664832599. Note that the first 3 decimals are identical.

The spelling of 255644640 in words is "two hundred fifty-five million, six hundred forty-four thousand, six hundred forty".