28811621 has 2 divisors, whose sum is σ = 28811622. Its totient is φ = 28811620.

The previous prime is 28811609. The next prime is 28811623. The reversal of 28811621 is 12611882.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20802721 + 8008900 = 4561^2 + 2830^2 .

It is a cyclic number.

It is not a de Polignac number, because 28811621 - 2¹⁴ = 28795237 is a prime.

Together with 28811623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28811623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14405810 + 14405811.

It is an arithmetic number, because the mean of its divisors is an integer number (14405811).

Almost surely, 2^28811621 is an apocalyptic number.

It is an amenable number.

28811621 is a deficient number, since it is larger than the sum of its proper divisors (1).

28811621 is an equidigital number, since it uses as much as digits as its factorization.

28811621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1536, while the sum is 29.

The square root of 28811621 is about 5367.6457595486. The cubic root of 28811621 is about 306.5649955704.

The spelling of 28811621 in words is "twenty-eight million, eight hundred eleven thousand, six hundred twenty-one".