1561405 has 4 divisors (see below), whose sum is σ = 1873692. Its totient is φ = 1249120.

The previous prime is 1561393. The next prime is 1561421. The reversal of 1561405 is 5041651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5041651 = 293 ⋅17207.

It can be written as a sum of positive squares in 2 ways, for example, as 887364 + 674041 = 942^2 + 821^2 .

It is not a de Polignac number, because 1561405 - 2⁹ = 1560893 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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, 156136 + ... + 156145.

It is an arithmetic number, because the mean of its divisors is an integer number (468423).

2^1561405 is an apocalyptic number.

It is an amenable number.

1561405 is a deficient number, since it is larger than the sum of its proper divisors (312287).

1561405 is an equidigital number, since it uses as much as digits as its factorization.

1561405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312286.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 1561405 is about 1249.5619232355. The cubic root of 1561405 is about 116.0126076269.

The spelling of 1561405 in words is "one million, five hundred sixty-one thousand, four hundred five".