66591397440 has 168 divisors, whose sum is σ = 230134290048. Its totient is φ = 17673384960.

The previous prime is 66591397423. The next prime is 66591397441. The reversal of 66591397440 is 4479319566.

66591397440 is a `hidden beast` number, since 6 + 6 + 591 + 3 + 9 + 7 + 4 + 40 = 666.

It is not an unprimeable number, because it can be changed into a prime (66591397441) 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, 552889 + ... + 662471.

Almost surely, 2^66591397440 is an apocalyptic number.

66591397440 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 66591397440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115067145024).

66591397440 is an abundant number, since it is smaller than the sum of its proper divisors (163542892608).

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

66591397440 is a wasteful number, since it uses less digits than its factorization.

66591397440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109817 (or 109804 counting only the distinct ones).

The product of its (nonzero) digits is 4898880, while the sum is 54.

The spelling of 66591397440 in words is "sixty-six billion, five hundred ninety-one million, three hundred ninety-seven thousand, four hundred forty".