28329021 has 40 divisors (see below), whose sum is σ = 51226560. Its totient is φ = 15230592.

The previous prime is 28329011. The next prime is 28329029. The reversal of 28329021 is 12092382.

It is a happy number.

It is not a de Polignac number, because 28329021 - 2¹¹ = 28326973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28329029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 8170 + ... + 11108.

It is an arithmetic number, because the mean of its divisors is an integer number (1280664).

Almost surely, 2^28329021 is an apocalyptic number.

28329021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28329021 is a deficient number, since it is larger than the sum of its proper divisors (22897539).

28329021 is a wasteful number, since it uses less digits than its factorization.

28329021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2975 (or 2966 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 28329021 is about 5322.5013856269. The cubic root of 28329021 is about 304.8436751538.

The spelling of 28329021 in words is "twenty-eight million, three hundred twenty-nine thousand, twenty-one".