66878987 has 4 divisors (see below), whose sum is σ = 76433136. Its totient is φ = 57324840.

The previous prime is 66878983. The next prime is 66879011. The reversal of 66878987 is 78987866.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66878987 - 2² = 66878983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66878983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4777064 + ... + 4777077.

It is an arithmetic number, because the mean of its divisors is an integer number (19108284).

Almost surely, 2^66878987 is an apocalyptic number.

66878987 is a deficient number, since it is larger than the sum of its proper divisors (9554149).

66878987 is an equidigital number, since it uses as much as digits as its factorization.

66878987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9554148.

The product of its digits is 8128512, while the sum is 59.

The square root of 66878987 is about 8177.9573855578. The cubic root of 66878987 is about 405.9101352548.

The spelling of 66878987 in words is "sixty-six million, eight hundred seventy-eight thousand, nine hundred eighty-seven".