28875721 has 16 divisors (see below), whose sum is σ = 33868800. Its totient is φ = 24108048.

The previous prime is 28875709. The next prime is 28875733. The reversal of 28875721 is 12757882.

It is an interprime number because it is at equal distance from previous prime (28875709) and next prime (28875733).

It is a cyclic number.

It is not a de Polignac number, because 28875721 - 2²³ = 20487113 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28875701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57156 + ... + 57658.

It is an arithmetic number, because the mean of its divisors is an integer number (2116800).

Almost surely, 2^28875721 is an apocalyptic number.

It is an amenable number.

28875721 is a deficient number, since it is larger than the sum of its proper divisors (4993079).

28875721 is a wasteful number, since it uses less digits than its factorization.

28875721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708.

The product of its digits is 62720, while the sum is 40.

The square root of 28875721 is about 5373.6134025440. The cubic root of 28875721 is about 306.7921754431.

The spelling of 28875721 in words is "twenty-eight million, eight hundred seventy-five thousand, seven hundred twenty-one".