1556561440 has 192 divisors, whose sum is σ = 4343673600. Its totient is φ = 526848000.

The previous prime is 1556561431. The next prime is 1556561443. The reversal of 1556561440 is 441656551.

It is a self number, because there is not a number n which added to its sum of digits gives 1556561440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1556561443) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6201315 + ... + 6201565.

It is an arithmetic number, because the mean of its divisors is an integer number (22623300).

Almost surely, 2^1556561440 is an apocalyptic number.

1556561440 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 1556561440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2171836800).

1556561440 is an abundant number, since it is smaller than the sum of its proper divisors (2787112160).

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

1556561440 is a wasteful number, since it uses less digits than its factorization.

1556561440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 400 (or 378 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 37.

The square root of 1556561440 is about 39453.2817392926. The cubic root of 1556561440 is about 1158.9252431345.

The spelling of 1556561440 in words is "one billion, five hundred fifty-six million, five hundred sixty-one thousand, four hundred forty".