1561840 has 40 divisors (see below), whose sum is σ = 4151520. Its totient is φ = 535296.

The previous prime is 1561829. The next prime is 1561883. The reversal of 1561840 is 481651.

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

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, 835 + ... + 1954.

It is an arithmetic number, because the mean of its divisors is an integer number (103788).

2^1561840 is an apocalyptic number.

1561840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561840 is an abundant number, since it is smaller than the sum of its proper divisors (2589680).

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

1561840 is a wasteful number, since it uses less digits than its factorization.

1561840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2809 (or 2803 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 1561840 is about 1249.7359721157. The cubic root of 1561840 is about 116.0233801466.

It can be divided in two parts, 1561 and 840, that added together give a 4-th power (2401 = 7⁴).

The spelling of 1561840 in words is "one million, five hundred sixty-one thousand, eight hundred forty".