55728509 has 4 divisors (see below), whose sum is σ = 56673120. Its totient is φ = 54783900.

The previous prime is 55728503. The next prime is 55728527. The reversal of 55728509 is 90582755.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55728509 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55728503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 472217 + ... + 472334.

It is an arithmetic number, because the mean of its divisors is an integer number (14168280).

Almost surely, 2^55728509 is an apocalyptic number.

55728509 is a gapful number since it is divisible by the number (59) formed by its first and last digit.

It is an amenable number.

55728509 is a deficient number, since it is larger than the sum of its proper divisors (944611).

55728509 is an equidigital number, since it uses as much as digits as its factorization.

55728509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 944610.

The product of its (nonzero) digits is 126000, while the sum is 41.

The square root of 55728509 is about 7465.1529790085. The cubic root of 55728509 is about 381.9669685354.

The spelling of 55728509 in words is "fifty-five million, seven hundred twenty-eight thousand, five hundred nine".