28578821 has 2 divisors, whose sum is σ = 28578822. Its totient is φ = 28578820.

The previous prime is 28578791. The next prime is 28578863. The reversal of 28578821 is 12887582.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28206721 + 372100 = 5311^2 + 610^2 .

It is a cyclic number.

It is not a de Polignac number, because 28578821 - 2¹⁰ = 28577797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28578881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14289410 + 14289411.

It is an arithmetic number, because the mean of its divisors is an integer number (14289411).

Almost surely, 2^28578821 is an apocalyptic number.

It is an amenable number.

28578821 is a deficient number, since it is larger than the sum of its proper divisors (1).

28578821 is an equidigital number, since it uses as much as digits as its factorization.

28578821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 71680, while the sum is 41.

The square root of 28578821 is about 5345.9162918998. The cubic root of 28578821 is about 305.7370724793.

The spelling of 28578821 in words is "twenty-eight million, five hundred seventy-eight thousand, eight hundred twenty-one".