57911991 has 4 divisors (see below), whose sum is σ = 77215992. Its totient is φ = 38607992.

The previous prime is 57911989. The next prime is 57912077. The reversal of 57911991 is 19911975.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 57911991 - 2¹ = 57911989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (57911921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9651996 + ... + 9652001.

It is an arithmetic number, because the mean of its divisors is an integer number (19303998).

Almost surely, 2^57911991 is an apocalyptic number.

57911991 is a deficient number, since it is larger than the sum of its proper divisors (19304001).

57911991 is a wasteful number, since it uses less digits than its factorization.

57911991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19304000.

The product of its digits is 25515, while the sum is 42.

The square root of 57911991 is about 7609.9928383672. The cubic root of 57911991 is about 386.8917764541.

The spelling of 57911991 in words is "fifty-seven million, nine hundred eleven thousand, nine hundred ninety-one".