66778540 has 48 divisors (see below), whose sum is σ = 150796800. Its totient is φ = 24760512.

The previous prime is 66778531. The next prime is 66778541. The reversal of 66778540 is 4587766.

It is not an unprimeable number, because it can be changed into a prime (66778541) 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, 15991 + ... + 19729.

It is an arithmetic number, because the mean of its divisors is an integer number (3141600).

Almost surely, 2^66778540 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 66778540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75398400).

66778540 is an abundant number, since it is smaller than the sum of its proper divisors (84018260).

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

66778540 is a wasteful number, since it uses less digits than its factorization.

66778540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3814 (or 3812 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 43.

The square root of 66778540 is about 8171.8137521605. The cubic root of 66778540 is about 405.7068183557.

The spelling of 66778540 in words is "sixty-six million, seven hundred seventy-eight thousand, five hundred forty".