550721621 has 2 divisors, whose sum is σ = 550721622. Its totient is φ = 550721620.

The previous prime is 550721609. The next prime is 550721623. The reversal of 550721621 is 126127055.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 529690225 + 21031396 = 23015^2 + 4586^2 .

It is a cyclic number.

It is not a de Polignac number, because 550721621 - 2⁶ = 550721557 is a prime.

Together with 550721623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (550721623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 275360810 + 275360811.

It is an arithmetic number, because the mean of its divisors is an integer number (275360811).

Almost surely, 2^550721621 is an apocalyptic number.

It is an amenable number.

550721621 is a deficient number, since it is larger than the sum of its proper divisors (1).

550721621 is an equidigital number, since it uses as much as digits as its factorization.

550721621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 550721621 is about 23467.4587674081. The cubic root of 550721621 is about 819.6794409320.

Adding to 550721621 its reverse (126127055), we get a palindrome (676848676).

The spelling of 550721621 in words is "five hundred fifty million, seven hundred twenty-one thousand, six hundred twenty-one".