66644220 has 48 divisors (see below), whose sum is σ = 187084800. Its totient is φ = 17726016.

The previous prime is 66644213. The next prime is 66644231. The reversal of 66644220 is 2244666.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a nialpdrome in base 10.

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, 26581 + ... + 28979.

It is an arithmetic number, because the mean of its divisors is an integer number (3897600).

Almost surely, 2^66644220 is an apocalyptic number.

66644220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66644220 is an abundant number, since it is smaller than the sum of its proper divisors (120440580).

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

66644220 is a wasteful number, since it uses less digits than its factorization.

66644220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2874 (or 2872 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 30.

The square root of 66644220 is about 8163.5911215592. The cubic root of 66644220 is about 405.4346195428.

Adding to 66644220 its reverse (2244666), we get a palindrome (68888886).

The spelling of 66644220 in words is "sixty-six million, six hundred forty-four thousand, two hundred twenty".