57721729 has 4 divisors (see below), whose sum is σ = 62161876. Its totient is φ = 53281584.

The previous prime is 57721691. The next prime is 57721759. The reversal of 57721729 is 92712775.

It is a happy number.

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 23814400 + 33907329 = 4880^2 + 5823^2 .

It is a cyclic number.

It is not a de Polignac number, because 57721729 - 2¹⁷ = 57590657 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 57721691 and 57721700.

It is not an unprimeable number, because it can be changed into a prime (57721759) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2220054 + ... + 2220079.

It is an arithmetic number, because the mean of its divisors is an integer number (15540469).

Almost surely, 2^57721729 is an apocalyptic number.

It is an amenable number.

57721729 is a deficient number, since it is larger than the sum of its proper divisors (4440147).

57721729 is a wasteful number, since it uses less digits than its factorization.

57721729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4440146.

The product of its digits is 61740, while the sum is 40.

The square root of 57721729 is about 7597.4817538445. The cubic root of 57721729 is about 386.4676181054.

The spelling of 57721729 in words is "fifty-seven million, seven hundred twenty-one thousand, seven hundred twenty-nine".