66542320 has 80 divisors (see below), whose sum is σ = 168426720. Its totient is φ = 24302592.

The previous prime is 66542279. The next prime is 66542321. The reversal of 66542320 is 2324566.

66542320 = 40² + 41² + ... + 584².

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66542321) 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 15 ways as a sum of consecutive naturals, for example, 113067 + ... + 113653.

It is an arithmetic number, because the mean of its divisors is an integer number (2105334).

Almost surely, 2^66542320 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66542320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84213360).

66542320 is an abundant number, since it is smaller than the sum of its proper divisors (101884400).

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

66542320 is a wasteful number, since it uses less digits than its factorization.

66542320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722 (or 716 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 28.

The square root of 66542320 is about 8157.3476081383. The cubic root of 66542320 is about 405.2278756216.

Adding to 66542320 its reverse (2324566), we get a palindrome (68866886).

The spelling of 66542320 in words is "sixty-six million, five hundred forty-two thousand, three hundred twenty".