28922821 has 2 divisors, whose sum is σ = 28922822. Its totient is φ = 28922820.

The previous prime is 28922779. The next prime is 28922827. The reversal of 28922821 is 12822982.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27196225 + 1726596 = 5215^2 + 1314^2 .

It is a cyclic number.

It is not a de Polignac number, because 28922821 - 2¹³ = 28914629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28922827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14461410 + 14461411.

It is an arithmetic number, because the mean of its divisors is an integer number (14461411).

Almost surely, 2^28922821 is an apocalyptic number.

It is an amenable number.

28922821 is a deficient number, since it is larger than the sum of its proper divisors (1).

28922821 is an equidigital number, since it uses as much as digits as its factorization.

28922821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 34.

The square root of 28922821 is about 5377.9941428008. The cubic root of 28922821 is about 306.9588906110.

The spelling of 28922821 in words is "twenty-eight million, nine hundred twenty-two thousand, eight hundred twenty-one".