561532781 has 4 divisors (see below), whose sum is σ = 562976700. Its totient is φ = 560088864.

The previous prime is 561532753. The next prime is 561532789. The reversal of 561532781 is 187235165.

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 300710281 + 260822500 = 17341^2 + 16150^2 .

It is a cyclic number.

It is not a de Polignac number, because 561532781 - 2¹⁸ = 561270637 is a prime.

It is a super-2 number, since 2×561532781² = 630638128275187922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561532789) 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, 721376 + ... + 722153.

It is an arithmetic number, because the mean of its divisors is an integer number (140744175).

Almost surely, 2^561532781 is an apocalyptic number.

It is an amenable number.

561532781 is a deficient number, since it is larger than the sum of its proper divisors (1443919).

561532781 is a wasteful number, since it uses less digits than its factorization.

561532781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1443918.

The product of its digits is 50400, while the sum is 38.

The square root of 561532781 is about 23696.6829113275. The cubic root of 561532781 is about 825.0084019959.

The spelling of 561532781 in words is "five hundred sixty-one million, five hundred thirty-two thousand, seven hundred eighty-one".