661645536 has 96 divisors (see below), whose sum is σ = 1798560288. Its totient is φ = 212828160.

The previous prime is 661645519. The next prime is 661645541. The reversal of 661645536 is 635546166.

It is a tau number, because it is divible by the number of its divisors (96).

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, 380926 + ... + 382658.

It is an arithmetic number, because the mean of its divisors is an integer number (18735003).

Almost surely, 2^661645536 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 661645536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (899280144).

661645536 is an abundant number, since it is smaller than the sum of its proper divisors (1136914752).

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

661645536 is a wasteful number, since it uses less digits than its factorization.

661645536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1884 (or 1876 counting only the distinct ones).

The product of its digits is 388800, while the sum is 42.

The square root of 661645536 is about 25722.4714209191. The cubic root of 661645536 is about 871.3817546264.

The spelling of 661645536 in words is "six hundred sixty-one million, six hundred forty-five thousand, five hundred thirty-six".