66778575 has 24 divisors (see below), whose sum is σ = 111928848. Its totient is φ = 35124480.

The previous prime is 66778573. The next prime is 66778577. The reversal of 66778575 is 57587766.

It is an interprime number because it is at equal distance from previous prime (66778573) and next prime (66778577).

It is not a de Polignac number, because 66778575 - 2¹ = 66778573 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66778571) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 624 + ... + 11573.

It is an arithmetic number, because the mean of its divisors is an integer number (4663702).

Almost surely, 2^66778575 is an apocalyptic number.

66778575 is a deficient number, since it is larger than the sum of its proper divisors (45150273).

66778575 is a wasteful number, since it uses less digits than its factorization.

66778575 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12283 (or 12278 counting only the distinct ones).

The product of its digits is 2469600, while the sum is 51.

The square root of 66778575 is about 8171.8158936677. The cubic root of 66778575 is about 405.7068892354.

It can be divided in two parts, 6677 and 8575, that multiplied together give a palindrome (57255275).

The spelling of 66778575 in words is "sixty-six million, seven hundred seventy-eight thousand, five hundred seventy-five".