1561565 has 4 divisors (see below), whose sum is σ = 1873884. Its totient is φ = 1249248.

The previous prime is 1561559. The next prime is 1561577. The reversal of 1561565 is 5651651.

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

It can be written as a sum of positive squares in 2 ways, for example, as 806404 + 755161 = 898^2 + 869^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561565 - 2¹² = 1557469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 156152 + ... + 156161.

It is an arithmetic number, because the mean of its divisors is an integer number (468471).

2^1561565 is an apocalyptic number.

It is an amenable number.

1561565 is a deficient number, since it is larger than the sum of its proper divisors (312319).

1561565 is an equidigital number, since it uses as much as digits as its factorization.

1561565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312318.

The product of its digits is 4500, while the sum is 29.

The square root of 1561565 is about 1249.6259440329. The cubic root of 1561565 is about 116.0165701656.

The spelling of 1561565 in words is "one million, five hundred sixty-one thousand, five hundred sixty-five".