28958750221 has 4 divisors (see below), whose sum is σ = 29665061244. Its totient is φ = 28252439200.

The previous prime is 28958750209. The next prime is 28958750237. The reversal of 28958750221 is 12205785982.

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 3202994025 + 25755756196 = 56595^2 + 160486^2 .

It is a cyclic number.

It is not a de Polignac number, because 28958750221 - 2²¹ = 28956653069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28958750021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 353155450 + ... + 353155531.

It is an arithmetic number, because the mean of its divisors is an integer number (7416265311).

Almost surely, 2^28958750221 is an apocalyptic number.

It is an amenable number.

28958750221 is a deficient number, since it is larger than the sum of its proper divisors (706311023).

28958750221 is an equidigital number, since it uses as much as digits as its factorization.

28958750221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 706311022.

The product of its (nonzero) digits is 806400, while the sum is 49.

The spelling of 28958750221 in words is "twenty-eight billion, nine hundred fifty-eight million, seven hundred fifty thousand, two hundred twenty-one".