65409991 has 4 divisors (see below), whose sum is σ = 65484952. Its totient is φ = 65335032.

The previous prime is 65409979. The next prime is 65410019. The reversal of 65409991 is 19990456.

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 65409991 - 2⁵ = 65409959 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 (65409901) 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, 36156 + ... + 37921.

It is an arithmetic number, because the mean of its divisors is an integer number (16371238).

Almost surely, 2^65409991 is an apocalyptic number.

65409991 is a deficient number, since it is larger than the sum of its proper divisors (74961).

65409991 is an equidigital number, since it uses as much as digits as its factorization.

65409991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74960.

The product of its (nonzero) digits is 87480, while the sum is 43.

The square root of 65409991 is about 8087.6443418340. The cubic root of 65409991 is about 402.9161694739.

The spelling of 65409991 in words is "sixty-five million, four hundred nine thousand, nine hundred ninety-one".