66211820 has 24 divisors (see below), whose sum is σ = 139243104. Its totient is φ = 26446976.

The previous prime is 66211807. The next prime is 66211823. The reversal of 66211820 is 2811266.

It is a self number, because there is not a number n which added to its sum of digits gives 66211820.

It is not an unprimeable number, because it can be changed into a prime (66211823) 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 7 ways as a sum of consecutive naturals, for example, 15209 + ... + 19071.

It is an arithmetic number, because the mean of its divisors is an integer number (5801796).

Almost surely, 2^66211820 is an apocalyptic number.

It is an amenable number.

66211820 is an abundant number, since it is smaller than the sum of its proper divisors (73031284).

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

66211820 is a wasteful number, since it uses less digits than its factorization.

66211820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4729 (or 4727 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 66211820 is about 8137.0645812848. The cubic root of 66211820 is about 404.5558714192. Note that the first 3 decimals are identical.

The spelling of 66211820 in words is "sixty-six million, two hundred eleven thousand, eight hundred twenty".