66655820 has 48 divisors (see below), whose sum is σ = 174521088. Its totient is φ = 20775360.

The previous prime is 66655807. The next prime is 66655829. The reversal of 66655820 is 2855666.

It is a happy number.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (66655829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20102 + ... + 23181.

It is an arithmetic number, because the mean of its divisors is an integer number (3635856).

Almost surely, 2^66655820 is an apocalyptic number.

It is an amenable number.

66655820 is an abundant number, since it is smaller than the sum of its proper divisors (107865268).

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

66655820 is a wasteful number, since it uses less digits than its factorization.

66655820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43310 (or 43308 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 38.

The square root of 66655820 is about 8164.3015622893. The cubic root of 66655820 is about 405.4581413063.

The spelling of 66655820 in words is "sixty-six million, six hundred fifty-five thousand, eight hundred twenty".