661288440616 has 8 divisors (see below), whose sum is σ = 1239915826170. Its totient is φ = 330644220304.

The previous prime is 661288440607. The next prime is 661288440619. The reversal of 661288440616 is 616044882166.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 433135096900 + 228153343716 = 658130^2 + 477654^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (661288440619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41330527531 + ... + 41330527546.

Almost surely, 2^661288440616 is an apocalyptic number.

It is an amenable number.

661288440616 is a deficient number, since it is larger than the sum of its proper divisors (578627385554).

661288440616 is a wasteful number, since it uses less digits than its factorization.

661288440616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82661055083 (or 82661055079 counting only the distinct ones).

The product of its (nonzero) digits is 2654208, while the sum is 52.

The spelling of 661288440616 in words is "six hundred sixty-one billion, two hundred eighty-eight million, four hundred forty thousand, six hundred sixteen".