556216721 has 8 divisors (see below), whose sum is σ = 562710120. Its totient is φ = 549739008.

The previous prime is 556216691. The next prime is 556216733. The reversal of 556216721 is 127612655.

It can be written as a sum of positive squares in 4 ways, for example, as 118570321 + 437646400 = 10889^2 + 20920^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 556216721 - 2¹⁰ = 556215697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (556216021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76955 + ... + 83871.

It is an arithmetic number, because the mean of its divisors is an integer number (70338765).

Almost surely, 2^556216721 is an apocalyptic number.

It is an amenable number.

556216721 is a deficient number, since it is larger than the sum of its proper divisors (6493399).

556216721 is an equidigital number, since it uses as much as digits as its factorization.

556216721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7843.

The product of its digits is 25200, while the sum is 35.

The square root of 556216721 is about 23584.2473062000. The cubic root of 556216721 is about 822.3966769999.

The spelling of 556216721 in words is "five hundred fifty-six million, two hundred sixteen thousand, seven hundred twenty-one".