66451220 has 48 divisors (see below), whose sum is σ = 153014400. Its totient is φ = 24040320.

The previous prime is 66451219. The next prime is 66451247. The reversal of 66451220 is 2215466.

It is a self number, because there is not a number n which added to its sum of digits gives 66451220.

It is a congruent number.

It is an unprimeable number.

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, 49721 + ... + 51039.

It is an arithmetic number, because the mean of its divisors is an integer number (3187800).

Almost surely, 2^66451220 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 66451220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (76507200).

66451220 is an abundant number, since it is smaller than the sum of its proper divisors (86563180).

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

66451220 is a wasteful number, since it uses less digits than its factorization.

66451220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1568 (or 1566 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 66451220 is about 8151.7617727704. The cubic root of 66451220 is about 405.0428649443.

Adding to 66451220 its reverse (2215466), we get a palindrome (68666686).

The spelling of 66451220 in words is "sixty-six million, four hundred fifty-one thousand, two hundred twenty".