64640521 has 8 divisors (see below), whose sum is σ = 70992000. Its totient is φ = 58368240.

The previous prime is 64640503. The next prime is 64640539. The reversal of 64640521 is 12504646.

64640521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (64640503) and next prime (64640539).

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 64640521 - 2⁷ = 64640393 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 64640521.

It is not an unprimeable number, because it can be changed into a prime (64640501) 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, 18081 + ... + 21358.

It is an arithmetic number, because the mean of its divisors is an integer number (8874000).

Almost surely, 2^64640521 is an apocalyptic number.

It is an amenable number.

64640521 is a deficient number, since it is larger than the sum of its proper divisors (6351479).

64640521 is a wasteful number, since it uses less digits than its factorization.

64640521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39599.

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 64640521 is about 8039.9328977299. The cubic root of 64640521 is about 401.3299916543.

The spelling of 64640521 in words is "sixty-four million, six hundred forty thousand, five hundred twenty-one".