1561145 has 4 divisors (see below), whose sum is σ = 1873380. Its totient is φ = 1248912.

The previous prime is 1561139. The next prime is 1561151. The reversal of 1561145 is 5411651.

1561145 = 883² + 884².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5411651 = 7 ⋅773093.

It is an interprime number because it is at equal distance from previous prime (1561139) and next prime (1561151).

It can be written as a sum of positive squares in 2 ways, for example, as 779689 + 781456 = 883^2 + 884^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561145 - 2¹⁰ = 1560121 is a prime.

It is a super-2 number, since 2×1561145² = 4874347422050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1561145.

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, 156110 + ... + 156119.

It is an arithmetic number, because the mean of its divisors is an integer number (468345).

2^1561145 is an apocalyptic number.

1561145 is the 884-th centered square number.

It is an amenable number.

1561145 is a deficient number, since it is larger than the sum of its proper divisors (312235).

1561145 is an equidigital number, since it uses as much as digits as its factorization.

1561145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312234.

The product of its digits is 600, while the sum is 23.

The square root of 1561145 is about 1249.4578824434. The cubic root of 1561145 is about 116.0061679241.

Adding to 1561145 its reverse (5411651), we get a palindrome (6972796).

The spelling of 1561145 in words is "one million, five hundred sixty-one thousand, one hundred forty-five".