64728321 has 16 divisors (see below), whose sum is σ = 99510144. Its totient is φ = 36658944.

The previous prime is 64728311. The next prime is 64728331. The reversal of 64728321 is 12382746.

It is an interprime number because it is at equal distance from previous prime (64728311) and next prime (64728331).

It is not a de Polignac number, because 64728321 - 2¹⁴ = 64711937 is a prime.

It is not an unprimeable number, because it can be changed into a prime (64728311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11266 + ... + 16011.

It is an arithmetic number, because the mean of its divisors is an integer number (6219384).

Almost surely, 2^64728321 is an apocalyptic number.

It is an amenable number.

64728321 is a deficient number, since it is larger than the sum of its proper divisors (34781823).

64728321 is a wasteful number, since it uses less digits than its factorization.

64728321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27400.

The product of its digits is 16128, while the sum is 33.

The square root of 64728321 is about 8045.3912894278. The cubic root of 64728321 is about 401.5116157652.

The spelling of 64728321 in words is "sixty-four million, seven hundred twenty-eight thousand, three hundred twenty-one".