511561 has 4 divisors (see below), whose sum is σ = 514692. Its totient is φ = 508432.

The previous prime is 511559. The next prime is 511573. The reversal of 511561 is 165115.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165115 = 5 ⋅33023.

It can be written as a sum of positive squares in 2 ways, for example, as 291600 + 219961 = 540^2 + 469^2 .

It is a cyclic number.

It is not a de Polignac number, because 511561 - 2¹ = 511559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (511541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1306 + ... + 1651.

It is an arithmetic number, because the mean of its divisors is an integer number (128673).

2⁵¹¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

511561 is a deficient number, since it is larger than the sum of its proper divisors (3131).

511561 is a wasteful number, since it uses less digits than its factorization.

511561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3130.

The product of its digits is 150, while the sum is 19.

The square root of 511561 is about 715.2349264403. The cubic root of 511561 is about 79.9771288787.

Adding to 511561 its reverse (165115), we get a palindrome (676676).

The spelling of 511561 in words is "five hundred eleven thousand, five hundred sixty-one".