661689544 has 16 divisors (see below), whose sum is σ = 1280689920. Its totient is φ = 320172240.

The previous prime is 661689533. The next prime is 661689551. The reversal of 661689544 is 445986166.

It is an unprimeable number.

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, 1333804 + ... + 1334299.

It is an arithmetic number, because the mean of its divisors is an integer number (80043120).

Almost surely, 2^661689544 is an apocalyptic number.

It is an amenable number.

661689544 is a deficient number, since it is larger than the sum of its proper divisors (619000376).

661689544 is a wasteful number, since it uses less digits than its factorization.

661689544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2668140 (or 2668136 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 49.

The square root of 661689544 is about 25723.3268454918. The cubic root of 661689544 is about 871.4010735900.

The spelling of 661689544 in words is "six hundred sixty-one million, six hundred eighty-nine thousand, five hundred forty-four".