1561866 has 16 divisors (see below), whose sum is σ = 3144864. Its totient is φ = 517104.

The previous prime is 1561829. The next prime is 1561883. The reversal of 1561866 is 6681651.

It is a zygodrome in base 4.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 180 + ... + 1776.

It is an arithmetic number, because the mean of its divisors is an integer number (196554).

2^1561866 is an apocalyptic number.

1561866 is an abundant number, since it is smaller than the sum of its proper divisors (1582998).

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

1561866 is a wasteful number, since it uses less digits than its factorization.

1561866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1765.

The product of its digits is 8640, while the sum is 33.

The square root of 1561866 is about 1249.7463742696. The cubic root of 1561866 is about 116.0240239580.

The spelling of 1561866 in words is "one million, five hundred sixty-one thousand, eight hundred sixty-six".