28890716721 has 4 divisors (see below), whose sum is σ = 38520955632. Its totient is φ = 19260477812.

The previous prime is 28890716681. The next prime is 28890716731. The reversal of 28890716721 is 12761709882.

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.

It is a cyclic number.

It is not a de Polignac number, because 28890716721 - 2¹⁷ = 28890585649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28890716731) 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, 4815119451 + ... + 4815119456.

It is an arithmetic number, because the mean of its divisors is an integer number (9630238908).

Almost surely, 2^28890716721 is an apocalyptic number.

It is an amenable number.

28890716721 is a deficient number, since it is larger than the sum of its proper divisors (9630238911).

28890716721 is an equidigital number, since it uses as much as digits as its factorization.

28890716721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9630238910.

The product of its (nonzero) digits is 677376, while the sum is 51.

The spelling of 28890716721 in words is "twenty-eight billion, eight hundred ninety million, seven hundred sixteen thousand, seven hundred twenty-one".