551621 has 4 divisors (see below), whose sum is σ = 630432. Its totient is φ = 472812.

The previous prime is 551597. The next prime is 551651. The reversal of 551621 is 126155.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 551621 - 2⁶ = 551557 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 551593 and 551602.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 551621.

It is not an unprimeable number, because it can be changed into a prime (551651) 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, 39395 + ... + 39408.

It is an arithmetic number, because the mean of its divisors is an integer number (157608).

2⁵⁵¹⁶²¹ is an apocalyptic number.

It is an amenable number.

551621 is a deficient number, since it is larger than the sum of its proper divisors (78811).

551621 is an equidigital number, since it uses as much as digits as its factorization.

551621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78810.

The product of its digits is 300, while the sum is 20.

The square root of 551621 is about 742.7119226187. The cubic root of 551621 is about 82.0125402197.

Adding to 551621 its reverse (126155), we get a palindrome (677776).

The spelling of 551621 in words is "five hundred fifty-one thousand, six hundred twenty-one".