551681 has 4 divisors (see below), whose sum is σ = 594132. Its totient is φ = 509232.

The previous prime is 551671. The next prime is 551689. The reversal of 551681 is 186155.

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 379456 + 172225 = 616^2 + 415^2 .

It is a cyclic number.

It is not a de Polignac number, because 551681 - 2¹⁰ = 550657 is a prime.

It is a super-2 number, since 2×551681² = 608703851522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 551681.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (551689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21206 + ... + 21231.

It is an arithmetic number, because the mean of its divisors is an integer number (148533).

2⁵⁵¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

551681 is a deficient number, since it is larger than the sum of its proper divisors (42451).

551681 is a wasteful number, since it uses less digits than its factorization.

551681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42450.

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

The square root of 551681 is about 742.7523140321. The cubic root of 551681 is about 82.0155136224.

The spelling of 551681 in words is "five hundred fifty-one thousand, six hundred eighty-one".