61666739 has 4 divisors (see below), whose sum is σ = 62075280. Its totient is φ = 61258200.

The previous prime is 61666729. The next prime is 61666757. The reversal of 61666739 is 93766616.

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 61666739 - 2⁸ = 61666483 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 61666739.

It is not an unprimeable number, because it can be changed into a prime (61666729) 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, 204044 + ... + 204345.

It is an arithmetic number, because the mean of its divisors is an integer number (15518820).

Almost surely, 2^61666739 is an apocalyptic number.

61666739 is a deficient number, since it is larger than the sum of its proper divisors (408541).

61666739 is a wasteful number, since it uses less digits than its factorization.

61666739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408540.

The product of its digits is 244944, while the sum is 44.

The square root of 61666739 is about 7852.8172651603. The cubic root of 61666739 is about 395.0787409119.

The spelling of 61666739 in words is "sixty-one million, six hundred sixty-six thousand, seven hundred thirty-nine".