1561871 has 4 divisors (see below), whose sum is σ = 1565544. Its totient is φ = 1558200.

The previous prime is 1561829. The next prime is 1561883. The reversal of 1561871 is 1781651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1781651 = 17 ⋅104803.

It is a cyclic number.

It is not a de Polignac number, because 1561871 - 2¹⁰ = 1560847 is a prime.

It is a Duffinian number.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1100 + ... + 2081.

It is an arithmetic number, because the mean of its divisors is an integer number (391386).

2^1561871 is an apocalyptic number.

1561871 is a deficient number, since it is larger than the sum of its proper divisors (3673).

1561871 is an equidigital number, since it uses as much as digits as its factorization.

1561871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3672.

The product of its digits is 1680, while the sum is 29.

The square root of 1561871 is about 1249.7483746739. The cubic root of 1561871 is about 116.0241477671.

The spelling of 1561871 in words is "one million, five hundred sixty-one thousand, eight hundred seventy-one".