655440 has 40 divisors (see below), whose sum is σ = 2032608. Its totient is φ = 174720.

The previous prime is 655439. The next prime is 655453. The reversal of 655440 is 44556.

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

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

It is a nialpdrome in base 10.

It is a zygodrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 655440.

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, 1126 + ... + 1605.

2⁶⁵⁵⁴⁴⁰ is an apocalyptic number.

655440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

655440 is an abundant number, since it is smaller than the sum of its proper divisors (1377168).

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

655440 is a wasteful number, since it uses less digits than its factorization.

655440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2747 (or 2741 counting only the distinct ones).

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

The square root of 655440 is about 809.5924900837. The cubic root of 655440 is about 86.8648979852.

Adding to 655440 its reverse (44556), we get a palindrome (699996).

The spelling of 655440 in words is "six hundred fifty-five thousand, four hundred forty".