728644021 has 8 divisors (see below), whose sum is σ = 881720640. Its totient is φ = 587813568.

The previous prime is 728643983. The next prime is 728644027. The reversal of 728644021 is 120446827.

It is a happy number.

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 728644021 - 2¹⁵ = 728611253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728644027) 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, 3061411 + ... + 3061648.

It is an arithmetic number, because the mean of its divisors is an integer number (110215080).

Almost surely, 2^728644021 is an apocalyptic number.

It is an amenable number.

728644021 is a deficient number, since it is larger than the sum of its proper divisors (153076619).

728644021 is a wasteful number, since it uses less digits than its factorization.

728644021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6123083.

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

The square root of 728644021 is about 26993.4069913377. The cubic root of 728644021 is about 899.8534827331.

The spelling of 728644021 in words is "seven hundred twenty-eight million, six hundred forty-four thousand, twenty-one".