561856381 has 2 divisors, whose sum is σ = 561856382. Its totient is φ = 561856380.

The previous prime is 561856367. The next prime is 561856417. The reversal of 561856381 is 183658165.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 561263481 + 592900 = 23691^2 + 770^2 .

It is a cyclic number.

It is not a de Polignac number, because 561856381 - 2⁵ = 561856349 is a prime.

It is a super-2 number, since 2×561856381² = 631365185740834322, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (561856481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280928190 + 280928191.

It is an arithmetic number, because the mean of its divisors is an integer number (280928191).

Almost surely, 2^561856381 is an apocalyptic number.

It is an amenable number.

561856381 is a deficient number, since it is larger than the sum of its proper divisors (1).

561856381 is an equidigital number, since it uses as much as digits as its factorization.

561856381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 172800, while the sum is 43.

The square root of 561856381 is about 23703.5098877782. The cubic root of 561856381 is about 825.1668501225.

The spelling of 561856381 in words is "five hundred sixty-one million, eight hundred fifty-six thousand, three hundred eighty-one".