28005557 has 2 divisors, whose sum is σ = 28005558. Its totient is φ = 28005556.

The previous prime is 28005553. The next prime is 28005569. The reversal of 28005557 is 75550082.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15888196 + 12117361 = 3986^2 + 3481^2 .

It is a cyclic number.

It is not a de Polignac number, because 28005557 - 2² = 28005553 is a prime.

It is a super-2 number, since 2×28005557² = 1568622445760498, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28005553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14002778 + 14002779.

It is an arithmetic number, because the mean of its divisors is an integer number (14002779).

Almost surely, 2^28005557 is an apocalyptic number.

It is an amenable number.

28005557 is a deficient number, since it is larger than the sum of its proper divisors (1).

28005557 is an equidigital number, since it uses as much as digits as its factorization.

28005557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14000, while the sum is 32.

The square root of 28005557 is about 5292.0276832231. The cubic root of 28005557 is about 303.6789843408.

The spelling of 28005557 in words is "twenty-eight million, five thousand, five hundred fifty-seven".