65999665216 has 63 divisors (see below), whose sum is σ = 139198956679. Its totient is φ = 31042224128.

The previous prime is 65999665213. The next prime is 65999665217. The reversal of 65999665216 is 61256699956.

The square root of 65999665216 is 256904.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 4939278400 + 61060386816 = 70280^2 + 247104^2 .

It is a Harshad number since it is a multiple of its sum of digits (64).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65999665213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 34938000 + ... + 34939888.

Almost surely, 2^65999665216 is an apocalyptic number.

65999665216 is the 256904-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65999665216

65999665216 is an abundant number, since it is smaller than the sum of its proper divisors (73199291463).

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

65999665216 is an frugal number, since it uses more digits than its factorization.

65999665216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3824 (or 1908 counting only the distinct ones).

The product of its digits is 47239200, while the sum is 64.

Multiplying 65999665216 by its sum of digits (64), we get a square (4223978573824 = 2055232²).

65999665216 divided by its sum of digits (64) gives a square (1031244769 = 32113²).

The spelling of 65999665216 in words is "sixty-five billion, nine hundred ninety-nine million, six hundred sixty-five thousand, two hundred sixteen".