1666631243656 has 8 divisors (see below), whose sum is σ = 3124933581870. Its totient is φ = 833315621824.

The previous prime is 1666631243653. The next prime is 1666631243671. The reversal of 1666631243656 is 6563421366661.

It can be written as a sum of positive squares in only one way, i.e., 1433599128900 + 233032114756 = 1197330^2 + 482734^2 .

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

It is a super-3 number, since 3×1666631243656³ (a number of 38 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (55) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 1666631243597 and 1666631243606.

It is not an unprimeable number, because it can be changed into a prime (1666631243653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104164452721 + ... + 104164452736.

Almost surely, 2^{1666631243656} is an apocalyptic number.

It is an amenable number.

1666631243656 is a deficient number, since it is larger than the sum of its proper divisors (1458302338214).

1666631243656 is a wasteful number, since it uses less digits than its factorization.

1666631243656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208328905463 (or 208328905459 counting only the distinct ones).

The product of its digits is 16796160, while the sum is 55.

The spelling of 1666631243656 in words is "one trillion, six hundred sixty-six billion, six hundred thirty-one million, two hundred forty-three thousand, six hundred fifty-six".