551921 has 4 divisors (see below), whose sum is σ = 563712. Its totient is φ = 540132.

The previous prime is 551917. The next prime is 551927. The reversal of 551921 is 129155.

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 551921 - 2² = 551917 is a prime.

It is an Ulam number.

It is a Duffinian number.

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 551921.

It is not an unprimeable number, because it can be changed into a prime (551927) 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 in 3 ways as a sum of consecutive naturals, for example, 5825 + ... + 5918.

It is an arithmetic number, because the mean of its divisors is an integer number (140928).

2⁵⁵¹⁹²¹ is an apocalyptic number.

It is an amenable number.

551921 is a deficient number, since it is larger than the sum of its proper divisors (11791).

551921 is a wasteful number, since it uses less digits than its factorization.

551921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11790.

The product of its digits is 450, while the sum is 23.

The square root of 551921 is about 742.9138577251. The cubic root of 551921 is about 82.0274050775.

The spelling of 551921 in words is "five hundred fifty-one thousand, nine hundred twenty-one".