661740129792 has 600 divisors, whose sum is σ = 2351331364536. Its totient is φ = 184647278592.

The previous prime is 661740129709. The next prime is 661740129811. The reversal of 661740129792 is 297921047166.

661740129792 is a `hidden beast` number, since 6 + 61 + 7 + 401 + 2 + 97 + 92 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 87377718 + ... + 87385290.

Almost surely, 2^661740129792 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 661740129792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1175665682268).

661740129792 is an abundant number, since it is smaller than the sum of its proper divisors (1689591234744).

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

661740129792 is an equidigital number, since it uses as much as digits as its factorization.

661740129792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7660 (or 7628 counting only the distinct ones).

The product of its (nonzero) digits is 2286144, while the sum is 54.

The spelling of 661740129792 in words is "six hundred sixty-one billion, seven hundred forty million, one hundred twenty-nine thousand, seven hundred ninety-two".