66213820 has 12 divisors (see below), whose sum is σ = 139049064. Its totient is φ = 26485520.

The previous prime is 66213817. The next prime is 66213821. The reversal of 66213820 is 2831266.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66213821) 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 3 ways as a sum of consecutive naturals, for example, 1655326 + ... + 1655365.

It is an arithmetic number, because the mean of its divisors is an integer number (11587422).

Almost surely, 2^66213820 is an apocalyptic number.

It is an amenable number.

66213820 is an abundant number, since it is smaller than the sum of its proper divisors (72835244).

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

66213820 is a wasteful number, since it uses less digits than its factorization.

66213820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3310700 (or 3310698 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 66213820 is about 8137.1874747974. The cubic root of 66213820 is about 404.5599447282.

The spelling of 66213820 in words is "sixty-six million, two hundred thirteen thousand, eight hundred twenty".