28721992 has 16 divisors (see below), whose sum is σ = 57996540. Its totient is φ = 13256256.

The previous prime is 28721989. The next prime is 28722011. The reversal of 28721992 is 29912782.

It can be written as a sum of positive squares in 2 ways, for example, as 28026436 + 695556 = 5294^2 + 834^2 .

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 137983 + ... + 138190.

Almost surely, 2^28721992 is an apocalyptic number.

It is an amenable number.

28721992 is an abundant number, since it is smaller than the sum of its proper divisors (29274548).

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

28721992 is a wasteful number, since it uses less digits than its factorization.

28721992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276192 (or 276188 counting only the distinct ones).

The product of its digits is 36288, while the sum is 40.

The square root of 28721992 is about 5359.2902515165. The cubic root of 28721992 is about 306.2467714778.

The spelling of 28721992 in words is "twenty-eight million, seven hundred twenty-one thousand, nine hundred ninety-two".