661166641 has 8 divisors (see below), whose sum is σ = 668297960. Its totient is φ = 654054912.

The previous prime is 661166633. The next prime is 661166651. The reversal of 661166641 is 146661166.

It can be written as a sum of positive squares in 4 ways, for example, as 94012416 + 567154225 = 9696^2 + 23815^2 .

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 661166641 - 2³ = 661166633 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 661166641.

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, 68851 + ... + 77863.

It is an arithmetic number, because the mean of its divisors is an integer number (83537245).

Almost surely, 2^661166641 is an apocalyptic number.

It is an amenable number.

661166641 is a deficient number, since it is larger than the sum of its proper divisors (7131319).

661166641 is a wasteful number, since it uses less digits than its factorization.

661166641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9795.

The product of its digits is 31104, while the sum is 37.

The square root of 661166641 is about 25713.1608519840. The cubic root of 661166641 is about 871.1714702858.

The spelling of 661166641 in words is "six hundred sixty-one million, one hundred sixty-six thousand, six hundred forty-one".