55072721 has 4 divisors (see below), whose sum is σ = 60079344. Its totient is φ = 50066100.

The previous prime is 55072681. The next prime is 55072747. The reversal of 55072721 is 12727055.

55072721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 55072721 - 2⁶ = 55072657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55072781) 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 in 3 ways as a sum of consecutive naturals, for example, 2503295 + ... + 2503316.

It is an arithmetic number, because the mean of its divisors is an integer number (15019836).

Almost surely, 2^55072721 is an apocalyptic number.

It is an amenable number.

55072721 is a deficient number, since it is larger than the sum of its proper divisors (5006623).

55072721 is a wasteful number, since it uses less digits than its factorization.

55072721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5006622.

The product of its (nonzero) digits is 4900, while the sum is 29.

The square root of 55072721 is about 7421.0997163493. The cubic root of 55072721 is about 380.4627810510.

Adding to 55072721 its reverse (12727055), we get a palindrome (67799776).

It can be divided in two parts, 5507 and 2721, that added together give a palindrome (8228).

The spelling of 55072721 in words is "fifty-five million, seventy-two thousand, seven hundred twenty-one".