65705991 has 8 divisors (see below), whose sum is σ = 94347120. Its totient is φ = 40434432.

The previous prime is 65705987. The next prime is 65705993. The reversal of 65705991 is 19950756.

65705991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 65705991 - 2² = 65705987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65705993) 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 7 ways as a sum of consecutive naturals, for example, 842346 + ... + 842423.

It is an arithmetic number, because the mean of its divisors is an integer number (11793390).

Almost surely, 2^65705991 is an apocalyptic number.

65705991 is a deficient number, since it is larger than the sum of its proper divisors (28641129).

65705991 is a wasteful number, since it uses less digits than its factorization.

65705991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1684785.

The product of its (nonzero) digits is 85050, while the sum is 42.

The square root of 65705991 is about 8105.9232046695. The cubic root of 65705991 is about 403.5230275120.

It can be divided in two parts, 6570 and 5991, that added together give a triangular number (12561 = T₁₅₈).

The spelling of 65705991 in words is "sixty-five million, seven hundred five thousand, nine hundred ninety-one".