564817721 has 4 divisors (see below), whose sum is σ = 608265252. Its totient is φ = 521370192.

The previous prime is 564817703. The next prime is 564817733. The reversal of 564817721 is 127718465.

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 218448400 + 346369321 = 14780^2 + 18611^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-564817721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (564817621) 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, 21723746 + ... + 21723771.

It is an arithmetic number, because the mean of its divisors is an integer number (152066313).

Almost surely, 2^564817721 is an apocalyptic number.

It is an amenable number.

564817721 is a deficient number, since it is larger than the sum of its proper divisors (43447531).

564817721 is a wasteful number, since it uses less digits than its factorization.

564817721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43447530.

The product of its digits is 94080, while the sum is 41.

The square root of 564817721 is about 23765.8940711264. The cubic root of 564817721 is about 826.6140283825.

The spelling of 564817721 in words is "five hundred sixty-four million, eight hundred seventeen thousand, seven hundred twenty-one".