1555840440 has 512 divisors, whose sum is σ = 6606489600. Its totient is φ = 316293120.

The previous prime is 1555840423. The next prime is 1555840453. The reversal of 1555840440 is 440485551.

It is a happy number.

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 = 1555840395 and 1555840404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 4407304 + ... + 4407656.

It is an arithmetic number, because the mean of its divisors is an integer number (12903300).

Almost surely, 2^1555840440 is an apocalyptic number.

1555840440 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 1555840440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3303244800).

1555840440 is an abundant number, since it is smaller than the sum of its proper divisors (5050649160).

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

1555840440 is a wasteful number, since it uses less digits than its factorization.

1555840440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 444 (or 434 counting only the distinct ones).

The product of its (nonzero) digits is 64000, while the sum is 36.

The square root of 1555840440 is about 39444.1432914951. The cubic root of 1555840440 is about 1158.7462772579.

The spelling of 1555840440 in words is "one billion, five hundred fifty-five million, eight hundred forty thousand, four hundred forty".