65571721 has 8 divisors (see below), whose sum is σ = 67455360. Its totient is φ = 63708528.

The previous prime is 65571719. The next prime is 65571749. The reversal of 65571721 is 12717556.

It is a happy number.

65571721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 65571721 - 2¹ = 65571719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65571791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1515 + ... + 11551.

It is an arithmetic number, because the mean of its divisors is an integer number (8431920).

Almost surely, 2^65571721 is an apocalyptic number.

It is an amenable number.

65571721 is a deficient number, since it is larger than the sum of its proper divisors (1883639).

65571721 is a wasteful number, since it uses less digits than its factorization.

65571721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10223.

The product of its digits is 14700, while the sum is 34.

The square root of 65571721 is about 8097.6367540166. The cubic root of 65571721 is about 403.2479740285.

The spelling of 65571721 in words is "sixty-five million, five hundred seventy-one thousand, seven hundred twenty-one".