661716628 has 6 divisors (see below), whose sum is σ = 1158004106. Its totient is φ = 330858312.

The previous prime is 661716623. The next prime is 661716677. The reversal of 661716628 is 826617166.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 634133124 + 27583504 = 25182^2 + 5252^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661716623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82714575 + ... + 82714582.

Almost surely, 2^661716628 is an apocalyptic number.

It is an amenable number.

661716628 is a deficient number, since it is larger than the sum of its proper divisors (496287478).

661716628 is a wasteful number, since it uses less digits than its factorization.

661716628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165429161 (or 165429159 counting only the distinct ones).

The product of its digits is 145152, while the sum is 43.

The square root of 661716628 is about 25723.8532883392. The cubic root of 661716628 is about 871.4129627027.

The spelling of 661716628 in words is "six hundred sixty-one million, seven hundred sixteen thousand, six hundred twenty-eight".