66800640 has 88 divisors (see below), whose sum is σ = 213706800. Its totient is φ = 17809408.

The previous prime is 66800611. The next prime is 66800647. The reversal of 66800640 is 4600866.

It is a happy number.

It is a hoax number, since the sum of its digits (30) 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 (30).

It is a junction number, because it is equal to n+sod(n) for n = 66800598 and 66800607.

It is not an unprimeable number, because it can be changed into a prime (66800647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13186 + ... + 17534.

Almost surely, 2^66800640 is an apocalyptic number.

66800640 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 66800640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (106853400).

66800640 is an abundant number, since it is smaller than the sum of its proper divisors (146906160).

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

66800640 is a wasteful number, since it uses less digits than its factorization.

66800640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4377 (or 4359 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 66800640 is about 8173.1658492900. The cubic root of 66800640 is about 405.7515689186.

The spelling of 66800640 in words is "sixty-six million, eight hundred thousand, six hundred forty".