28219381 has 2 divisors, whose sum is σ = 28219382. Its totient is φ = 28219380.

The previous prime is 28219361. The next prime is 28219421. The reversal of 28219381 is 18391282.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24354225 + 3865156 = 4935^2 + 1966^2 .

It is a cyclic number.

It is not a de Polignac number, because 28219381 - 2²³ = 19830773 is a prime.

It is a super-2 number, since 2×28219381² = 1592666928046322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28219361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14109690 + 14109691.

It is an arithmetic number, because the mean of its divisors is an integer number (14109691).

Almost surely, 2^28219381 is an apocalyptic number.

It is an amenable number.

28219381 is a deficient number, since it is larger than the sum of its proper divisors (1).

28219381 is an equidigital number, since it uses as much as digits as its factorization.

28219381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 34.

The square root of 28219381 is about 5312.1917322326. The cubic root of 28219381 is about 304.4498943748.

The spelling of 28219381 in words is "twenty-eight million, two hundred nineteen thousand, three hundred eighty-one".