66691335808440 has 288 divisors, whose sum is σ = 252639392850000. Its totient is φ = 15213183326208.

The previous prime is 66691335808397. The next prime is 66691335808441. The reversal of 66691335808440 is 4480853319666.

It is a super-2 number, since 2×66691335808440² (a number of 28 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66691335808441) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 5014096 + ... + 12590624.

Almost surely, 2^{66691335808440} is an apocalyptic number.

66691335808440 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 66691335808440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (126319696425000).

66691335808440 is an abundant number, since it is smaller than the sum of its proper divisors (185948057041560).

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

66691335808440 is a wasteful number, since it uses less digits than its factorization.

66691335808440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7577059 (or 7577045 counting only the distinct ones).

The product of its (nonzero) digits is 89579520, while the sum is 63.

The spelling of 66691335808440 in words is "sixty-six trillion, six hundred ninety-one billion, three hundred thirty-five million, eight hundred eight thousand, four hundred forty".