61666661 has 8 divisors (see below), whose sum is σ = 71174784. Its totient is φ = 52333200.

The previous prime is 61666651. The next prime is 61666681. The reversal of 61666661 is 16666616.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61666661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61666651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42905 + ... + 44318.

It is an arithmetic number, because the mean of its divisors is an integer number (8896848).

Almost surely, 2^61666661 is an apocalyptic number.

It is an amenable number.

61666661 is a deficient number, since it is larger than the sum of its proper divisors (9508123).

61666661 is a wasteful number, since it uses less digits than its factorization.

61666661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87331.

The product of its digits is 46656, while the sum is 38.

The square root of 61666661 is about 7852.8122987883. The cubic root of 61666661 is about 395.0785743383.

The spelling of 61666661 in words is "sixty-one million, six hundred sixty-six thousand, six hundred sixty-one".