66781440 has 432 divisors, whose sum is σ = 275498496. Its totient is φ = 14745600.

The previous prime is 66781391. The next prime is 66781453. The reversal of 66781440 is 4418766.

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 = 66781395 and 66781404.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2154225 + ... + 2154255.

It is an arithmetic number, because the mean of its divisors is an integer number (637728).

Almost surely, 2^66781440 is an apocalyptic number.

66781440 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 66781440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137749248).

66781440 is an abundant number, since it is smaller than the sum of its proper divisors (208717056).

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

66781440 is a wasteful number, since it uses less digits than its factorization.

66781440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 66781440 is about 8171.9911894226. The cubic root of 66781440 is about 405.7126911642.

It can be divided in two parts, 6678 and 1440, that added together give a palindrome (8118).

The spelling of 66781440 in words is "sixty-six million, seven hundred eighty-one thousand, four hundred forty".