64725521 has 6 divisors (see below), whose sum is σ = 75293010. Its totient is φ = 55478976.

The previous prime is 64725503. The next prime is 64725541. The reversal of 64725521 is 12552746.

64725521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 64577296 + 148225 = 8036^2 + 385^2 .

It is a de Polignac number, because none of the positive numbers 2^k-64725521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64725541) 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 5 ways as a sum of consecutive naturals, for example, 660416 + ... + 660513.

It is an arithmetic number, because the mean of its divisors is an integer number (12548835).

Almost surely, 2^64725521 is an apocalyptic number.

It is an amenable number.

64725521 is a deficient number, since it is larger than the sum of its proper divisors (10567489).

64725521 is a wasteful number, since it uses less digits than its factorization.

64725521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1320943 (or 1320936 counting only the distinct ones).

The product of its digits is 16800, while the sum is 32.

The square root of 64725521 is about 8045.2172748783. The cubic root of 64725521 is about 401.5058261886.

The spelling of 64725521 in words is "sixty-four million, seven hundred twenty-five thousand, five hundred twenty-one".