550138721 has 6 divisors (see below), whose sum is σ = 604698066. Its totient is φ = 500126000.

The previous prime is 550138663. The next prime is 550138723. The reversal of 550138721 is 127831055.

It can be written as a sum of positive squares in only one way, i.e., 546390625 + 3748096 = 23375^2 + 1936^2 .

It is a de Polignac number, because none of the positive numbers 2^k-550138721 is a prime.

It is a super-2 number, since 2×550138721² = 605305224687031682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (550138723) 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 in 5 ways as a sum of consecutive naturals, for example, 2273180 + ... + 2273421.

It is an arithmetic number, because the mean of its divisors is an integer number (100783011).

Almost surely, 2^550138721 is an apocalyptic number.

It is an amenable number.

550138721 is a deficient number, since it is larger than the sum of its proper divisors (54559345).

550138721 is a wasteful number, since it uses less digits than its factorization.

550138721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4546623 (or 4546612 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 32.

The square root of 550138721 is about 23455.0361543102. The cubic root of 550138721 is about 819.3901478805.

Adding to 550138721 its reverse (127831055), we get a palindrome (677969776).

The spelling of 550138721 in words is "five hundred fifty million, one hundred thirty-eight thousand, seven hundred twenty-one".