1555840 has 128 divisors (see below), whose sum is σ = 4626720. Its totient is φ = 491520.

The previous prime is 1555837. The next prime is 1555847. The reversal of 1555840 is 485551.

It is a tau number, because it is divible by the number of its divisors (128).

It is a junction number, because it is equal to n+sod(n) for n = 1555799 and 1555808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1555847) 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 15 ways as a sum of consecutive naturals, for example, 91512 + ... + 91528.

2^1555840 is an apocalyptic number.

1555840 is a gapful number since it is divisible by the number (10) 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 1555840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2313360).

1555840 is an abundant number, since it is smaller than the sum of its proper divisors (3070880).

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

1555840 is a wasteful number, since it uses less digits than its factorization.

1555840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 28.

The square root of 1555840 is about 1247.3331551755. Note that the first 3 decimals coincide. The cubic root of 1555840 is about 115.8746168025.

It can be divided in two parts, 155 and 5840, that added together give a palindrome (5995).

The spelling of 1555840 in words is "one million, five hundred fifty-five thousand, eight hundred forty".