661761751089600 has 2688 divisors, whose sum is σ = 2968647991511040. Its totient is φ = 141714800640000.

The previous prime is 661761751089581. The next prime is 661761751089643. The reversal of 661761751089600 is 6980157167166.

661761751089600 is a `hidden beast` number, since 6 + 6 + 1 + 7 + 6 + 1 + 7 + 5 + 10 + 8 + 9 + 600 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 94523886100 + ... + 94523893100.

Almost surely, 2^{661761751089600} is an apocalyptic number.

661761751089600 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 661761751089600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1484323995755520).

661761751089600 is an abundant number, since it is smaller than the sum of its proper divisors (2306886240421440).

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

661761751089600 is a wasteful number, since it uses less digits than its factorization.

661761751089600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7295 (or 7262 counting only the distinct ones).

The product of its (nonzero) digits is 22861440, while the sum is 63.

The spelling of 661761751089600 in words is "six hundred sixty-one trillion, seven hundred sixty-one billion, seven hundred fifty-one million, eighty-nine thousand, six hundred".