56617721 has 4 divisors (see below), whose sum is σ = 56655732. Its totient is φ = 56579712.

The previous prime is 56617711. The next prime is 56617723. The reversal of 56617721 is 12771665.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12771665 = 5 ⋅2554333.

It can be written as a sum of positive squares in 2 ways, for example, as 22231225 + 34386496 = 4715^2 + 5864^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-56617721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (56617723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16676 + ... + 19781.

It is an arithmetic number, because the mean of its divisors is an integer number (14163933).

Almost surely, 2^56617721 is an apocalyptic number.

It is an amenable number.

56617721 is a deficient number, since it is larger than the sum of its proper divisors (38011).

56617721 is a wasteful number, since it uses less digits than its factorization.

56617721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38010.

The product of its digits is 17640, while the sum is 35.

The square root of 56617721 is about 7524.4747989478. The cubic root of 56617721 is about 383.9878310127.

The spelling of 56617721 in words is "fifty-six million, six hundred seventeen thousand, seven hundred twenty-one".