549665621 has 4 divisors (see below), whose sum is σ = 549794700. Its totient is φ = 549536544.

The previous prime is 549665609. The next prime is 549665659. The reversal of 549665621 is 126566945.

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 137007025 + 412658596 = 11705^2 + 20314^2 .

It is a cyclic number.

It is not a de Polignac number, because 549665621 - 2¹⁰ = 549664597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (549665671) 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, 57926 + ... + 66743.

It is an arithmetic number, because the mean of its divisors is an integer number (137448675).

Almost surely, 2^549665621 is an apocalyptic number.

It is an amenable number.

549665621 is a deficient number, since it is larger than the sum of its proper divisors (129079).

549665621 is a wasteful number, since it uses less digits than its factorization.

549665621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129078.

The product of its digits is 388800, while the sum is 44.

The square root of 549665621 is about 23444.9487310167. The cubic root of 549665621 is about 819.1551982578.

It can be divided in two parts, 5496 and 65621, that added together give a palindrome (71117).

The spelling of 549665621 in words is "five hundred forty-nine million, six hundred sixty-five thousand, six hundred twenty-one".