661669189 has 4 divisors (see below), whose sum is σ = 700590924. Its totient is φ = 622747456.

The previous prime is 661669171. The next prime is 661669199. The reversal of 661669189 is 981966166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 346890625 + 314778564 = 18625^2 + 17742^2 .

It is a cyclic number.

It is not a de Polignac number, because 661669189 - 2⁹ = 661668677 is a prime.

It is a super-2 number, since 2×661669189² = 875612231343835442, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661669139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19460842 + ... + 19460875.

It is an arithmetic number, because the mean of its divisors is an integer number (175147731).

Almost surely, 2^661669189 is an apocalyptic number.

It is an amenable number.

661669189 is a deficient number, since it is larger than the sum of its proper divisors (38921735).

661669189 is a wasteful number, since it uses less digits than its factorization.

661669189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38921734.

The product of its digits is 839808, while the sum is 52.

The square root of 661669189 is about 25722.9311898936. The cubic root of 661669189 is about 871.3921381052.

The spelling of 661669189 in words is "six hundred sixty-one million, six hundred sixty-nine thousand, one hundred eighty-nine".