28942721 has 8 divisors (see below), whose sum is σ = 30735360. Its totient is φ = 27160128.

The previous prime is 28942699. The next prime is 28942723. The reversal of 28942721 is 12724982.

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 28942721 - 2²² = 24748417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28942723) 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 7 ways as a sum of consecutive naturals, for example, 3920 + ... + 8558.

It is an arithmetic number, because the mean of its divisors is an integer number (3841920).

Almost surely, 2^28942721 is an apocalyptic number.

It is an amenable number.

28942721 is a deficient number, since it is larger than the sum of its proper divisors (1792639).

28942721 is a wasteful number, since it uses less digits than its factorization.

28942721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5023.

The product of its digits is 16128, while the sum is 35.

The square root of 28942721 is about 5379.8439568448. The cubic root of 28942721 is about 307.0292742653.

The spelling of 28942721 in words is "twenty-eight million, nine hundred forty-two thousand, seven hundred twenty-one".