551861 has 2 divisors, whose sum is σ = 551862. Its totient is φ = 551860.

The previous prime is 551849. The next prime is 551909. The reversal of 551861 is 168155.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 481636 + 70225 = 694^2 + 265^2 .

It is a cyclic number.

It is not a de Polignac number, because 551861 - 2¹⁸ = 289717 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is equal to p₄₅₄₆₇ and since 551861 and 45467 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 551861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (551801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 275930 + 275931.

It is an arithmetic number, because the mean of its divisors is an integer number (275931).

2⁵⁵¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

551861 is a deficient number, since it is larger than the sum of its proper divisors (1).

551861 is an equidigital number, since it uses as much as digits as its factorization.

551861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1200, while the sum is 26.

The square root of 551861 is about 742.8734750952. The cubic root of 551861 is about 82.0244325370.

The spelling of 551861 in words is "five hundred fifty-one thousand, eight hundred sixty-one".