28062721 has 4 divisors (see below), whose sum is σ = 28126512. Its totient is φ = 27998932.

The previous prime is 28062707. The next prime is 28062731. The reversal of 28062721 is 12726082.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12726082 = 2 ⋅6363041.

It is a cyclic number.

It is not a de Polignac number, because 28062721 - 2²³ = 19674113 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28062721.

It is not an unprimeable number, because it can be changed into a prime (28062731) 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, 31231 + ... + 32116.

It is an arithmetic number, because the mean of its divisors is an integer number (7031628).

Almost surely, 2^28062721 is an apocalyptic number.

It is an amenable number.

28062721 is a deficient number, since it is larger than the sum of its proper divisors (63791).

28062721 is an equidigital number, since it uses as much as digits as its factorization.

28062721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63790.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 28062721 is about 5297.4258843329. The cubic root of 28062721 is about 303.8854636909.

It can be divided in two parts, 280 and 62721, that added together give a square (63001 = 251²).

The spelling of 28062721 in words is "twenty-eight million, sixty-two thousand, seven hundred twenty-one".