66688440 has 256 divisors, whose sum is σ = 255467520. Its totient is φ = 13547520.

The previous prime is 66688439. The next prime is 66688451. The reversal of 66688440 is 4488666.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 66688392 and 66688401.

It is a congruent number.

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, 338422 + ... + 338618.

It is an arithmetic number, because the mean of its divisors is an integer number (997920).

Almost surely, 2^66688440 is an apocalyptic number.

66688440 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 66688440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127733760).

66688440 is an abundant number, since it is smaller than the sum of its proper divisors (188779080).

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

66688440 is a wasteful number, since it uses less digits than its factorization.

66688440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262 (or 258 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 42.

The square root of 66688440 is about 8166.2990393446. The cubic root of 66688440 is about 405.5242715039.

The spelling of 66688440 in words is "sixty-six million, six hundred eighty-eight thousand, four hundred forty".