661065784 has 64 divisors (see below), whose sum is σ = 1343664000. Its totient is φ = 303937920.

The previous prime is 661065773. The next prime is 661065809. The reversal of 661065784 is 487560166.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 661065784.

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 15 ways as a sum of consecutive naturals, for example, 769147 + ... + 770005.

It is an arithmetic number, because the mean of its divisors is an integer number (20994750).

Almost surely, 2^661065784 is an apocalyptic number.

It is an amenable number.

661065784 is an abundant number, since it is smaller than the sum of its proper divisors (682598216).

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

661065784 is a wasteful number, since it uses less digits than its factorization.

661065784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1028 (or 1024 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 43.

The square root of 661065784 is about 25711.1995830611. The cubic root of 661065784 is about 871.1271707081.

The spelling of 661065784 in words is "six hundred sixty-one million, sixty-five thousand, seven hundred eighty-four".