661166605 has 16 divisors (see below), whose sum is σ = 893449728. Its totient is φ = 465336000.

The previous prime is 661166603. The next prime is 661166609. The reversal of 661166605 is 506661166.

It is not a de Polignac number, because 661166605 - 2¹ = 661166603 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 (661166603) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 192186 + ... + 195595.

It is an arithmetic number, because the mean of its divisors is an integer number (55840608).

Almost surely, 2^661166605 is an apocalyptic number.

It is an amenable number.

661166605 is a deficient number, since it is larger than the sum of its proper divisors (232283123).

661166605 is a wasteful number, since it uses less digits than its factorization.

661166605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387828.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 661166605 is about 25713.1601519533. The cubic root of 661166605 is about 871.1714544743.

The spelling of 661166605 in words is "six hundred sixty-one million, one hundred sixty-six thousand, six hundred five".