28655509 has 8 divisors (see below), whose sum is σ = 29703960. Its totient is φ = 27611136.

The previous prime is 28655503. The next prime is 28655581. The reversal of 28655509 is 90555682.

It can be written as a sum of positive squares in 4 ways, for example, as 15186609 + 13468900 = 3897^2 + 3670^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28655509 - 2¹⁹ = 28131221 is a prime.

It is a super-2 number, since 2×28655509² = 1642276392098162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28655503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24277 + ... + 25429.

It is an arithmetic number, because the mean of its divisors is an integer number (3712995).

Almost surely, 2^28655509 is an apocalyptic number.

28655509 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

28655509 is a deficient number, since it is larger than the sum of its proper divisors (1048451).

28655509 is a wasteful number, since it uses less digits than its factorization.

28655509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2039.

The product of its (nonzero) digits is 108000, while the sum is 40.

The square root of 28655509 is about 5353.0840643502. The cubic root of 28655509 is about 306.0102983989.

The spelling of 28655509 in words is "twenty-eight million, six hundred fifty-five thousand, five hundred nine".