66821860 has 48 divisors (see below), whose sum is σ = 168819840. Its totient is φ = 21703680.

The previous prime is 66821857. The next prime is 66821891. The reversal of 66821860 is 6812866.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9901 + ... + 15220.

It is an arithmetic number, because the mean of its divisors is an integer number (3517080).

Almost surely, 2^66821860 is an apocalyptic number.

It is an amenable number.

66821860 is an abundant number, since it is smaller than the sum of its proper divisors (101997980).

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

66821860 is a wasteful number, since it uses less digits than its factorization.

66821860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25156 (or 25154 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 66821860 is about 8174.4638967947. The cubic root of 66821860 is about 405.7945282713.

The spelling of 66821860 in words is "sixty-six million, eight hundred twenty-one thousand, eight hundred sixty".