55057721 has 4 divisors (see below), whose sum is σ = 55083600. Its totient is φ = 55031844.

The previous prime is 55057703. The next prime is 55057741. The reversal of 55057721 is 12775055.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12775055 = 5 ⋅2555011.

It is a cyclic number.

It is not a de Polignac number, because 55057721 - 2⁶ = 55057657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55057741) 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, 9431 + ... + 14108.

It is an arithmetic number, because the mean of its divisors is an integer number (13770900).

Almost surely, 2^55057721 is an apocalyptic number.

It is an amenable number.

55057721 is a deficient number, since it is larger than the sum of its proper divisors (25879).

55057721 is a wasteful number, since it uses less digits than its factorization.

55057721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25878.

The product of its (nonzero) digits is 12250, while the sum is 32.

The square root of 55057721 is about 7420.0890156386. The cubic root of 55057721 is about 380.4282360602.

The spelling of 55057721 in words is "fifty-five million, fifty-seven thousand, seven hundred twenty-one".