66251520 has 252 divisors, whose sum is σ = 241281936. Its totient is φ = 17418240.

The previous prime is 66251503. The next prime is 66251527. The reversal of 66251520 is 2515266.

66251520 is a `hidden beast` number, since 6 + 625 + 15 + 20 = 666.

66251520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (66251527) 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 27 ways as a sum of consecutive naturals, for example, 933085 + ... + 933155.

It is an arithmetic number, because the mean of its divisors is an integer number (957468).

Almost surely, 2^66251520 is an apocalyptic number.

66251520 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66251520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120640968).

66251520 is an abundant number, since it is smaller than the sum of its proper divisors (175030416).

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

66251520 is an frugal number, since it uses more digits than its factorization.

66251520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110 (or 81 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 66251520 is about 8139.5036703720. The cubic root of 66251520 is about 404.6367112611.

Adding to 66251520 its reverse (2515266), we get a palindrome (68766786).

It can be divided in two parts, 6 and 6251520, that added together give a palindrome (6251526).

The spelling of 66251520 in words is "sixty-six million, two hundred fifty-one thousand, five hundred twenty".