661678977600 has 1344 divisors, whose sum is σ = 2729962414080. Its totient is φ = 154983628800.

The previous prime is 661678977581. The next prime is 661678977611. The reversal of 661678977600 is 6779876166.

661678977600 is a `hidden beast` number, since 6 + 6 + 16 + 7 + 8 + 9 + 7 + 7 + 600 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 726321145 + ... + 726322055.

Almost surely, 2^661678977600 is an apocalyptic number.

661678977600 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661678977600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1364981207040).

661678977600 is an abundant number, since it is smaller than the sum of its proper divisors (2068283436480).

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

661678977600 is a wasteful number, since it uses less digits than its factorization.

661678977600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1025 (or 1004 counting only the distinct ones).

The product of its (nonzero) digits is 32006016, while the sum is 63.

The spelling of 661678977600 in words is "six hundred sixty-one billion, six hundred seventy-eight million, nine hundred seventy-seven thousand, six hundred".