65699991 has 20 divisors (see below), whose sum is σ = 112166032. Its totient is φ = 37542528.

The previous prime is 65699969. The next prime is 65700013. The reversal of 65699991 is 19999656.

65699991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (65699969) and next prime (65700013).

It is not a de Polignac number, because 65699991 - 2⁹ = 65699479 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 (65699191) 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 19 ways as a sum of consecutive naturals, for example, 57370 + ... + 58503.

Almost surely, 2^65699991 is an apocalyptic number.

65699991 is a deficient number, since it is larger than the sum of its proper divisors (46466041).

65699991 is a wasteful number, since it uses less digits than its factorization.

65699991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115892 (or 115883 counting only the distinct ones).

The product of its digits is 1180980, while the sum is 54.

The square root of 65699991 is about 8105.5530964889. The cubic root of 65699991 is about 403.5107444521.

The spelling of 65699991 in words is "sixty-five million, six hundred ninety-nine thousand, nine hundred ninety-one".