661166661 has 8 divisors (see below), whose sum is σ = 883469664. Its totient is φ = 439820720.

The previous prime is 661166659. The next prime is 661166687. The reversal of 661166661 is 166661166.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 661166661 - 2¹ = 661166659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661166651) 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, 237651 + ... + 240416.

It is an arithmetic number, because the mean of its divisors is an integer number (110433708).

Almost surely, 2^661166661 is an apocalyptic number.

It is an amenable number.

661166661 is a deficient number, since it is larger than the sum of its proper divisors (222303003).

661166661 is a wasteful number, since it uses less digits than its factorization.

661166661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478531.

The product of its digits is 46656, while the sum is 39.

The square root of 661166661 is about 25713.1612408898. The cubic root of 661166661 is about 871.1714790700.

The spelling of 661166661 in words is "six hundred sixty-one million, one hundred sixty-six thousand, six hundred sixty-one".