65091978 has 64 divisors (see below), whose sum is σ = 172523520. Its totient is φ = 17786736.

The previous prime is 65091977. The next prime is 65092009. The reversal of 65091978 is 87919056.

65091978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (65091973) 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 31 ways as a sum of consecutive naturals, for example, 4951 + ... + 12437.

It is an arithmetic number, because the mean of its divisors is an integer number (2695680).

Almost surely, 2^65091978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65091978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86261760).

65091978 is an abundant number, since it is smaller than the sum of its proper divisors (107431542).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

65091978 is a wasteful number, since it uses less digits than its factorization.

65091978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7528 (or 7522 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The square root of 65091978 is about 8067.9599651957. The cubic root of 65091978 is about 402.2621368918.

The spelling of 65091978 in words is "sixty-five million, ninety-one thousand, nine hundred seventy-eight".