57191721 has 4 divisors (see below), whose sum is σ = 76255632. Its totient is φ = 38127812.

The previous prime is 57191711. The next prime is 57191747. The reversal of 57191721 is 12719175.

57191721 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 57191721 - 2⁶ = 57191657 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (57191711) 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, 9531951 + ... + 9531956.

It is an arithmetic number, because the mean of its divisors is an integer number (19063908).

Almost surely, 2^57191721 is an apocalyptic number.

It is an amenable number.

57191721 is a deficient number, since it is larger than the sum of its proper divisors (19063911).

57191721 is a wasteful number, since it uses less digits than its factorization.

57191721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19063910.

The product of its digits is 4410, while the sum is 33.

The square root of 57191721 is about 7562.5208098887. The cubic root of 57191721 is about 385.2811147542.

The spelling of 57191721 in words is "fifty-seven million, one hundred ninety-one thousand, seven hundred twenty-one".