66860640 has 480 divisors, whose sum is σ = 298577664. Its totient is φ = 13685760.

The previous prime is 66860611. The next prime is 66860641. The reversal of 66860640 is 4606866.

66860640 is a `hidden beast` number, since 6 + 6 + 8 + 6 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

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 = 66860595 and 66860604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66860641) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 997887 + ... + 997953.

Almost surely, 2^66860640 is an apocalyptic number.

66860640 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 66860640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149288832).

66860640 is an abundant number, since it is smaller than the sum of its proper divisors (231717024).

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

66860640 is a wasteful number, since it uses less digits than its factorization.

66860640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112 (or 95 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 66860640 is about 8176.8355737412. The cubic root of 66860640 is about 405.8730139072.

The spelling of 66860640 in words is "sixty-six million, eight hundred sixty thousand, six hundred forty".