65553721 has 4 divisors (see below), whose sum is σ = 65619700. Its totient is φ = 65487744.

The previous prime is 65553713. The next prime is 65553727. The reversal of 65553721 is 12735556.

65553721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 14930496 + 50623225 = 3864^2 + 7115^2 .

It is a cyclic number.

It is not a de Polignac number, because 65553721 - 2³ = 65553713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65553727) 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 3 ways as a sum of consecutive naturals, for example, 31476 + ... + 33493.

It is an arithmetic number, because the mean of its divisors is an integer number (16404925).

Almost surely, 2^65553721 is an apocalyptic number.

It is an amenable number.

65553721 is a deficient number, since it is larger than the sum of its proper divisors (65979).

65553721 is a wasteful number, since it uses less digits than its factorization.

65553721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65978.

The product of its digits is 31500, while the sum is 34.

The square root of 65553721 is about 8096.5252423493. The cubic root of 65553721 is about 403.2110723088.

The spelling of 65553721 in words is "sixty-five million, five hundred fifty-three thousand, seven hundred twenty-one".