66688889040 has 240 divisors, whose sum is σ = 228836134800. Its totient is φ = 17400987648.

The previous prime is 66688889021. The next prime is 66688889041. The reversal of 66688889040 is 4098888666.

It can be written as a sum of positive squares in 8 ways, for example, as 1179510336 + 65509378704 = 34344^2 + 255948^2 .

It is a tau number, because it is divible by the number of its divisors (240).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66688889041) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6210396 + ... + 6221124.

It is an arithmetic number, because the mean of its divisors is an integer number (953483895).

Almost surely, 2^66688889040 is an apocalyptic number.

66688889040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66688889040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114418067400).

66688889040 is an abundant number, since it is smaller than the sum of its proper divisors (162147245760).

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

66688889040 is a wasteful number, since it uses less digits than its factorization.

66688889040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10934 (or 10925 counting only the distinct ones).

The product of its (nonzero) digits is 31850496, while the sum is 63.

The spelling of 66688889040 in words is "sixty-six billion, six hundred eighty-eight million, eight hundred eighty-nine thousand, forty".