65991947 has 4 divisors (see below), whose sum is σ = 75419376. Its totient is φ = 56564520.

The previous prime is 65991931. The next prime is 65991949. The reversal of 65991947 is 74919956.

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 65991947 - 2⁴ = 65991931 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 65991895 and 65991904.

It is not an unprimeable number, because it can be changed into a prime (65991949) 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, 4713704 + ... + 4713717.

It is an arithmetic number, because the mean of its divisors is an integer number (18854844).

Almost surely, 2^65991947 is an apocalyptic number.

65991947 is a deficient number, since it is larger than the sum of its proper divisors (9427429).

65991947 is an equidigital number, since it uses as much as digits as its factorization.

65991947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9427428.

The product of its digits is 612360, while the sum is 50.

The square root of 65991947 is about 8123.5427616281. The cubic root of 65991947 is about 404.1075649766.

The spelling of 65991947 in words is "sixty-five million, nine hundred ninety-one thousand, nine hundred forty-seven".