28355981 has 2 divisors, whose sum is σ = 28355982. Its totient is φ = 28355980.

The previous prime is 28355953. The next prime is 28356019. The reversal of 28355981 is 18955382.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24900100 + 3455881 = 4990^2 + 1859^2 .

It is a cyclic number.

It is not a de Polignac number, because 28355981 - 2¹⁰ = 28354957 is a prime.

It is a super-2 number, since 2×28355981² = 1608123316944722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28355281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14177990 + 14177991.

It is an arithmetic number, because the mean of its divisors is an integer number (14177991).

Almost surely, 2^28355981 is an apocalyptic number.

It is an amenable number.

28355981 is a deficient number, since it is larger than the sum of its proper divisors (1).

28355981 is an equidigital number, since it uses as much as digits as its factorization.

28355981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 86400, while the sum is 41.

The square root of 28355981 is about 5325.0334271251. The cubic root of 28355981 is about 304.9403484524.

The spelling of 28355981 in words is "twenty-eight million, three hundred fifty-five thousand, nine hundred eighty-one".