64728421 has 4 divisors (see below), whose sum is σ = 68135200. Its totient is φ = 61321644.

The previous prime is 64728409. The next prime is 64728439. The reversal of 64728421 is 12482746.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 64728421 - 2⁹ = 64727909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64728481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1703361 + ... + 1703398.

It is an arithmetic number, because the mean of its divisors is an integer number (17033800).

Almost surely, 2^64728421 is an apocalyptic number.

It is an amenable number.

64728421 is a deficient number, since it is larger than the sum of its proper divisors (3406779).

64728421 is a wasteful number, since it uses less digits than its factorization.

64728421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3406778.

The product of its digits is 21504, while the sum is 34.

The square root of 64728421 is about 8045.3975041635. The cubic root of 64728421 is about 401.5118225328.

The spelling of 64728421 in words is "sixty-four million, seven hundred twenty-eight thousand, four hundred twenty-one".