661644754000 has 80 divisors (see below), whose sum is σ = 1600717547520. Its totient is φ = 264515548800.

The previous prime is 661644753953. The next prime is 661644754027. The reversal of 661644754000 is 457446166.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 3669969 + ... + 3846031.

It is an arithmetic number, because the mean of its divisors is an integer number (20008969344).

Almost surely, 2^661644754000 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 661644754000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (800358773760).

661644754000 is an abundant number, since it is smaller than the sum of its proper divisors (939072793520).

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

661644754000 is a wasteful number, since it uses less digits than its factorization.

661644754000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177965 (or 177949 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 43.

The spelling of 661644754000 in words is "six hundred sixty-one billion, six hundred forty-four million, seven hundred fifty-four thousand".