561491 has 8 divisors (see below), whose sum is σ = 655200. Its totient is φ = 480984.

The previous prime is 561461. The next prime is 561521. The reversal of 561491 is 194165.

It is an interprime number because it is at equal distance from previous prime (561461) and next prime (561521).

It is a de Polignac number, because none of the positive numbers 2^k-561491 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 561491.

It is not an unprimeable number, because it can be changed into a prime (561461) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 476 + ... + 1161.

It is an arithmetic number, because the mean of its divisors is an integer number (81900).

2⁵⁶¹⁴⁹¹ is an apocalyptic number.

561491 is a deficient number, since it is larger than the sum of its proper divisors (93709).

561491 is an equidigital number, since it uses as much as digits as its factorization.

561491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1658 (or 1644 counting only the distinct ones).

The product of its digits is 1080, while the sum is 26.

The square root of 561491 is about 749.3270314089. The cubic root of 561491 is about 82.4987939830.

The spelling of 561491 in words is "five hundred sixty-one thousand, four hundred ninety-one".