56999991 has 4 divisors (see below), whose sum is σ = 75999992. Its totient is φ = 37999992.

The previous prime is 56999989. The next prime is 57000011. The reversal of 56999991 is 19999965.

56999991 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.

It is not a de Polignac number, because 56999991 - 2¹ = 56999989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56999191) 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, 9499996 + ... + 9500001.

It is an arithmetic number, because the mean of its divisors is an integer number (18999998).

Almost surely, 2^56999991 is an apocalyptic number.

56999991 is a deficient number, since it is larger than the sum of its proper divisors (19000001).

56999991 is a wasteful number, since it uses less digits than its factorization.

56999991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19000000.

The product of its digits is 1771470, while the sum is 57.

The square root of 56999991 is about 7549.8338392312. The cubic root of 56999991 is about 384.8500928724.

It can be divided in two parts, 5 and 6999991, that added together give a palindrome (6999996).

The spelling of 56999991 in words is "fifty-six million, nine hundred ninety-nine thousand, nine hundred ninety-one".