661745924808156 has 192 divisors, whose sum is σ = 1861025822328960. Its totient is φ = 202525346119680.

The previous prime is 661745924808097. The next prime is 661745924808211. The reversal of 661745924808156 is 651808429547166.

661745924808156 is a `hidden beast` number, since 6 + 6 + 1 + 7 + 4 + 5 + 92 + 480 + 8 + 1 + 56 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 877115266 + ... + 877869398.

It is an arithmetic number, because the mean of its divisors is an integer number (9692842824630).

Almost surely, 2^{661745924808156} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661745924808156, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (930512911164480).

661745924808156 is an abundant number, since it is smaller than the sum of its proper divisors (1199279897520804).

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

661745924808156 is a wasteful number, since it uses less digits than its factorization.

661745924808156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 765861 (or 765853 counting only the distinct ones).

The product of its (nonzero) digits is 696729600, while the sum is 72.

The spelling of 661745924808156 in words is "six hundred sixty-one trillion, seven hundred forty-five billion, nine hundred twenty-four million, eight hundred eight thousand, one hundred fifty-six".