661492675684 has 9 divisors (see below), whose sum is σ = 1157615029081. Its totient is φ = 330745524520.

The previous prime is 661492675663. The next prime is 661492675687. The reversal of 661492675684 is 486576294166.

The square root of 661492675684 is 813322.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 4938997284 + 656553678400 = 70278^2 + 810280^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661492675687) 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 2 ways as a sum of consecutive naturals, for example, 1423314 + ... + 1829974.

Almost surely, 2^661492675684 is an apocalyptic number.

661492675684 is the 813322-nd square number.

It is an amenable number.

661492675684 is a deficient number, since it is larger than the sum of its proper divisors (496122353397).

661492675684 is an frugal number, since it uses more digits than its factorization.

661492675684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813326 (or 406663 counting only the distinct ones).

The product of its digits is 104509440, while the sum is 64.

Multiplying 661492675684 by its sum of digits (64), we get a square (42335531243776 = 6506576²).

The spelling of 661492675684 in words is "six hundred sixty-one billion, four hundred ninety-two million, six hundred seventy-five thousand, six hundred eighty-four".