66888782640 has 320 divisors, whose sum is σ = 234036449280. Its totient is φ = 17776122624.

The previous prime is 66888782633. The next prime is 66888782749. The reversal of 66888782640 is 4628788866.

66888782640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×66888782640² (a number of 22 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 77506849 + ... + 77507711.

It is an arithmetic number, because the mean of its divisors is an integer number (731363904).

Almost surely, 2^66888782640 is an apocalyptic number.

66888782640 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 66888782640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117018224640).

66888782640 is an abundant number, since it is smaller than the sum of its proper divisors (167147666640).

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

66888782640 is an equidigital number, since it uses as much as digits as its factorization.

66888782640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1340 (or 1316 counting only the distinct ones).

The product of its (nonzero) digits is 49545216, while the sum is 63.

The spelling of 66888782640 in words is "sixty-six billion, eight hundred eighty-eight million, seven hundred eighty-two thousand, six hundred forty".