66819618 has 48 divisors (see below), whose sum is σ = 155675520. Its totient is φ = 20647008.

The previous prime is 66819617. The next prime is 66819647. The reversal of 66819618 is 81691866.

It is a happy number.

It is a super-2 number, since 2×66819618² = 8929722699331848, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66819611) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13996 + ... + 18152.

It is an arithmetic number, because the mean of its divisors is an integer number (3243240).

Almost surely, 2^66819618 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66819618, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77837760).

66819618 is an abundant number, since it is smaller than the sum of its proper divisors (88855902).

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

66819618 is a wasteful number, since it uses less digits than its factorization.

66819618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4231 (or 4228 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 66819618 is about 8174.3267612691. The cubic root of 66819618 is about 405.7899898288.

The spelling of 66819618 in words is "sixty-six million, eight hundred nineteen thousand, six hundred eighteen".