1561255 has 4 divisors (see below), whose sum is σ = 1873512. Its totient is φ = 1249000.

The previous prime is 1561247. The next prime is 1561267. The reversal of 1561255 is 5521651.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1561255 - 2³ = 1561247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 156121 + ... + 156130.

It is an arithmetic number, because the mean of its divisors is an integer number (468378).

2^1561255 is an apocalyptic number.

1561255 is a deficient number, since it is larger than the sum of its proper divisors (312257).

1561255 is an equidigital number, since it uses as much as digits as its factorization.

1561255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312256.

The product of its digits is 1500, while the sum is 25.

The square root of 1561255 is about 1249.5019007589. The cubic root of 1561255 is about 116.0088925010.

It can be divided in two parts, 156125 and 5, that multiplied together give a triangular number (780625 = T₁₂₄₉).

The spelling of 1561255 in words is "one million, five hundred sixty-one thousand, two hundred fifty-five".