66815320 has 64 divisors (see below), whose sum is σ = 176631840. Its totient is φ = 22425600.

The previous prime is 66815297. The next prime is 66815339. The reversal of 66815320 is 2351866.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 121 + ... + 11560.

Almost surely, 2^66815320 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 66815320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88315920).

66815320 is an abundant number, since it is smaller than the sum of its proper divisors (109816520).

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

66815320 is a wasteful number, since it uses less digits than its factorization.

66815320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11716 (or 11712 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 66815320 is about 8174.0638607733. The cubic root of 66815320 is about 405.7812891766.

The spelling of 66815320 in words is "sixty-six million, eight hundred fifteen thousand, three hundred twenty".