66719640 has 128 divisors (see below), whose sum is σ = 227001600. Its totient is φ = 15552000.

The previous prime is 66719581. The next prime is 66719647. The reversal of 66719640 is 4691766.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66719647) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28515 + ... + 30765.

It is an arithmetic number, because the mean of its divisors is an integer number (1773450).

Almost surely, 2^66719640 is an apocalyptic number.

66719640 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 66719640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113500800).

66719640 is an abundant number, since it is smaller than the sum of its proper divisors (160281960).

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

66719640 is a wasteful number, since it uses less digits than its factorization.

66719640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2297 (or 2293 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 39.

The square root of 66719640 is about 8168.2091060403. The cubic root of 66719640 is about 405.5875027758.

The spelling of 66719640 in words is "sixty-six million, seven hundred nineteen thousand, six hundred forty".