66726640 has 80 divisors (see below), whose sum is σ = 160882560. Its totient is φ = 25724160.

The previous prime is 66726631. The next prime is 66726641. The reversal of 66726640 is 4662766.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 66726640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66726641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 316135 + ... + 316345.

It is an arithmetic number, because the mean of its divisors is an integer number (2011032).

Almost surely, 2^66726640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66726640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80441280).

66726640 is an abundant number, since it is smaller than the sum of its proper divisors (94155920).

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

66726640 is a wasteful number, since it uses less digits than its factorization.

66726640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350 (or 344 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 37.

The square root of 66726640 is about 8168.6375853015. The cubic root of 66726640 is about 405.6016865716.

The spelling of 66726640 in words is "sixty-six million, seven hundred twenty-six thousand, six hundred forty".