66779988 has 48 divisors (see below), whose sum is σ = 171702720. Its totient is φ = 20032000.

The previous prime is 66779987. The next prime is 66780031. The reversal of 66779988 is 88997766.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66779981) 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, 10828 + ... + 15836.

It is an arithmetic number, because the mean of its divisors is an integer number (3577140).

Almost surely, 2^66779988 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66779988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85851360).

66779988 is an abundant number, since it is smaller than the sum of its proper divisors (104922732).

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

66779988 is a wasteful number, since it uses less digits than its factorization.

66779988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5128 (or 5126 counting only the distinct ones).

The product of its digits is 9144576, while the sum is 60.

The square root of 66779988 is about 8171.9023489026. The cubic root of 66779988 is about 405.7097507310.

The spelling of 66779988 in words is "sixty-six million, seven hundred seventy-nine thousand, nine hundred eighty-eight".