66385440 has 288 divisors, whose sum is σ = 257402880. Its totient is φ = 15966720.

The previous prime is 66385433. The next prime is 66385447. The reversal of 66385440 is 4458366.

It is an interprime number because it is at equal distance from previous prime (66385433) and next prime (66385447).

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 66385395 and 66385404.

It is not an unprimeable number, because it can be changed into a prime (66385447) 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, 522657 + ... + 522783.

It is an arithmetic number, because the mean of its divisors is an integer number (893760).

Almost surely, 2^66385440 is an apocalyptic number.

66385440 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 66385440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128701440).

66385440 is an abundant number, since it is smaller than the sum of its proper divisors (191017440).

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

66385440 is a wasteful number, since it uses less digits than its factorization.

66385440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 148 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 66385440 is about 8147.7260631418. The cubic root of 66385440 is about 404.9091703032.

The spelling of 66385440 in words is "sixty-six million, three hundred eighty-five thousand, four hundred forty".