561557 has 4 divisors (see below), whose sum is σ = 563340. Its totient is φ = 559776.

The previous prime is 561553. The next prime is 561559. The reversal of 561557 is 755165.

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 538756 + 22801 = 734^2 + 151^2 .

It is a cyclic number.

It is not a de Polignac number, because 561557 - 2² = 561553 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561551) 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, 278 + ... + 1095.

It is an arithmetic number, because the mean of its divisors is an integer number (140835).

2⁵⁶¹⁵⁵⁷ is an apocalyptic number.

It is an amenable number.

561557 is a deficient number, since it is larger than the sum of its proper divisors (1783).

561557 is a wasteful number, since it uses less digits than its factorization.

561557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1782.

The product of its digits is 5250, while the sum is 29.

The square root of 561557 is about 749.3710696311. The cubic root of 561557 is about 82.5020262741.

The spelling of 561557 in words is "five hundred sixty-one thousand, five hundred fifty-seven".