28155649 has 2 divisors, whose sum is σ = 28155650. Its totient is φ = 28155648.

The previous prime is 28155641. The next prime is 28155671. The reversal of 28155649 is 94655182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16459249 + 11696400 = 4057^2 + 3420^2 .

It is a cyclic number.

It is not a de Polignac number, because 28155649 - 2³ = 28155641 is a prime.

It is a super-2 number, since 2×28155649² = 1585481141222402, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (28155641) 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, 14077824 + 14077825.

It is an arithmetic number, because the mean of its divisors is an integer number (14077825).

Almost surely, 2^28155649 is an apocalyptic number.

It is an amenable number.

28155649 is a deficient number, since it is larger than the sum of its proper divisors (1).

28155649 is an equidigital number, since it uses as much as digits as its factorization.

28155649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 86400, while the sum is 40.

The square root of 28155649 is about 5306.1896875253. The cubic root of 28155649 is about 304.2205268813.

It can be divided in two parts, 2815 and 5649, that added together give a square (8464 = 92²).

The spelling of 28155649 in words is "twenty-eight million, one hundred fifty-five thousand, six hundred forty-nine".