64821728 has 48 divisors (see below), whose sum is σ = 137803680. Its totient is φ = 29922816.

The previous prime is 64821727. The next prime is 64821767. The reversal of 64821728 is 82712846.

It is a junction number, because it is equal to n+sod(n) for n = 64821691 and 64821700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64821721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19826 + ... + 22862.

It is an arithmetic number, because the mean of its divisors is an integer number (2870910).

Almost surely, 2^64821728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64821728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68901840).

64821728 is an abundant number, since it is smaller than the sum of its proper divisors (72981952).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

64821728 is a wasteful number, since it uses less digits than its factorization.

64821728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3099 (or 3091 counting only the distinct ones).

The product of its digits is 43008, while the sum is 38.

The square root of 64821728 is about 8051.1941971362. The cubic root of 64821728 is about 401.7046583632.

The spelling of 64821728 in words is "sixty-four million, eight hundred twenty-one thousand, seven hundred twenty-eight".