28411721 has 4 divisors (see below), whose sum is σ = 30597252. Its totient is φ = 26226192.

The previous prime is 28411699. The next prime is 28411753. The reversal of 28411721 is 12711482.

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 16605625 + 11806096 = 4075^2 + 3436^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28411721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28411771) 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, 1092746 + ... + 1092771.

It is an arithmetic number, because the mean of its divisors is an integer number (7649313).

Almost surely, 2^28411721 is an apocalyptic number.

It is an amenable number.

28411721 is a deficient number, since it is larger than the sum of its proper divisors (2185531).

28411721 is a wasteful number, since it uses less digits than its factorization.

28411721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2185530.

The product of its digits is 896, while the sum is 26.

The square root of 28411721 is about 5330.2646275771. The cubic root of 28411721 is about 305.1400270763.

The spelling of 28411721 in words is "twenty-eight million, four hundred eleven thousand, seven hundred twenty-one".