28721824 has 12 divisors (see below), whose sum is σ = 56546154. Its totient is φ = 14360896.

The previous prime is 28721809. The next prime is 28721831. The reversal of 28721824 is 42812782.

It can be written as a sum of positive squares in only one way, i.e., 28430224 + 291600 = 5332^2 + 540^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 28721824.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 448747 + ... + 448810.

Almost surely, 2^28721824 is an apocalyptic number.

It is an amenable number.

28721824 is a deficient number, since it is larger than the sum of its proper divisors (27824330).

28721824 is an equidigital number, since it uses as much as digits as its factorization.

28721824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 897567 (or 897559 counting only the distinct ones).

The product of its digits is 14336, while the sum is 34.

The square root of 28721824 is about 5359.2745777764. The cubic root of 28721824 is about 306.2461743795.

The spelling of 28721824 in words is "twenty-eight million, seven hundred twenty-one thousand, eight hundred twenty-four".