28963721 has 4 divisors (see below), whose sum is σ = 29962500. Its totient is φ = 27964944.

The previous prime is 28963717. The next prime is 28963757. The reversal of 28963721 is 12736982.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14440000 + 14523721 = 3800^2 + 3811^2 .

It is a cyclic number.

It is not a de Polignac number, because 28963721 - 2² = 28963717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28963321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 499346 + ... + 499403.

It is an arithmetic number, because the mean of its divisors is an integer number (7490625).

Almost surely, 2^28963721 is an apocalyptic number.

It is an amenable number.

28963721 is a deficient number, since it is larger than the sum of its proper divisors (998779).

28963721 is an equidigital number, since it uses as much as digits as its factorization.

28963721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 998778.

The product of its digits is 36288, while the sum is 38.

The square root of 28963721 is about 5381.7953324146. The cubic root of 28963721 is about 307.1035134956.

The spelling of 28963721 in words is "twenty-eight million, nine hundred sixty-three thousand, seven hundred twenty-one".