66648640 has 28 divisors (see below), whose sum is σ = 158707836. Its totient is φ = 26659328.

The previous prime is 66648611. The next prime is 66648649. The reversal of 66648640 is 4684666.

It can be written as a sum of positive squares in 2 ways, for example, as 8156736 + 58491904 = 2856^2 + 7648^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 66648593 and 66648602.

It is not an unprimeable number, because it can be changed into a prime (66648649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 103819 + ... + 104458.

It is an arithmetic number, because the mean of its divisors is an integer number (5668137).

Almost surely, 2^66648640 is an apocalyptic number.

It is an amenable number.

66648640 is an abundant number, since it is smaller than the sum of its proper divisors (92059196).

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

66648640 is a wasteful number, since it uses less digits than its factorization.

66648640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208294 (or 208284 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 40.

The square root of 66648640 is about 8163.8618312659. The cubic root of 66648640 is about 405.4435824676.

The spelling of 66648640 in words is "sixty-six million, six hundred forty-eight thousand, six hundred forty".