66687861 has 4 divisors (see below), whose sum is σ = 88917152. Its totient is φ = 44458572.

The previous prime is 66687839. The next prime is 66687871. The reversal of 66687861 is 16878666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 66687861 - 2⁹ = 66687349 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66687861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66687811) 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, 11114641 + ... + 11114646.

It is an arithmetic number, because the mean of its divisors is an integer number (22229288).

Almost surely, 2^66687861 is an apocalyptic number.

It is an amenable number.

66687861 is a deficient number, since it is larger than the sum of its proper divisors (22229291).

66687861 is a wasteful number, since it uses less digits than its factorization.

66687861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22229290.

The product of its digits is 580608, while the sum is 48.

The square root of 66687861 is about 8166.2635886922. The cubic root of 66687861 is about 405.5230978910.

The spelling of 66687861 in words is "sixty-six million, six hundred eighty-seven thousand, eight hundred sixty-one".