1511561 has 4 divisors (see below), whose sum is σ = 1552452. Its totient is φ = 1470672.

The previous prime is 1511539. The next prime is 1511563. The reversal of 1511561 is 1651151.

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 1452025 + 59536 = 1205^2 + 244^2 .

It is a cyclic number.

It is not a de Polignac number, because 1511561 - 2¹⁴ = 1495177 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1511563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20390 + ... + 20463.

It is an arithmetic number, because the mean of its divisors is an integer number (388113).

2^1511561 is an apocalyptic number.

It is an amenable number.

1511561 is a deficient number, since it is larger than the sum of its proper divisors (40891).

1511561 is an equidigital number, since it uses as much as digits as its factorization.

1511561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40890.

The product of its digits is 150, while the sum is 20.

The square root of 1511561 is about 1229.4555705677. The cubic root of 1511561 is about 114.7647617325.

The spelling of 1511561 in words is "one million, five hundred eleven thousand, five hundred sixty-one".