67666661 has 4 divisors (see below), whose sum is σ = 67871424. Its totient is φ = 67461900.

The previous prime is 67666639. The next prime is 67666691. The reversal of 67666661 is 16666676.

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 a cyclic number.

It is not a de Polignac number, because 67666661 - 2⁶ = 67666597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (67666601) 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, 101885 + ... + 102546.

It is an arithmetic number, because the mean of its divisors is an integer number (16967856).

Almost surely, 2^67666661 is an apocalyptic number.

It is an amenable number.

67666661 is a deficient number, since it is larger than the sum of its proper divisors (204763).

67666661 is a wasteful number, since it uses less digits than its factorization.

67666661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204762.

The product of its digits is 326592, while the sum is 44.

The square root of 67666661 is about 8225.9747750647. The cubic root of 67666661 is about 407.4974689644.

It can be divided in two parts, 6 and 7666661, that added together give a palindrome (7666667).

The spelling of 67666661 in words is "sixty-seven million, six hundred sixty-six thousand, six hundred sixty-one".