661661857476 has 27 divisors (see below), whose sum is σ = 1672546476783. Its totient is φ = 220552325640.

The previous prime is 661661857433. The next prime is 661661857499. The reversal of 661661857476 is 674758166166.

The square root of 661661857476 is 813426.

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

661661857476 is a `hidden beast` number, since 6 + 6 + 1 + 6 + 618 + 5 + 7 + 4 + 7 + 6 = 666.

It is a super-3 number, since 3×661661857476³ (a number of 36 digits) contains 333 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4812771 + ... + 4948341.

Almost surely, 2^661661857476 is an apocalyptic number.

661661857476 is the 813426-th square number.

It is an amenable number.

661661857476 is an abundant number, since it is smaller than the sum of its proper divisors (1010884619307).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661661857476 is an frugal number, since it uses more digits than its factorization.

661661857476 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271152 (or 135576 counting only the distinct ones).

The product of its digits is 60963840, while the sum is 63.

The spelling of 661661857476 in words is "six hundred sixty-one billion, six hundred sixty-one million, eight hundred fifty-seven thousand, four hundred seventy-six".