661761776 has 40 divisors (see below), whose sum is σ = 1382359440. Its totient is φ = 305081856.

The previous prime is 661761769. The next prime is 661761803. The reversal of 661761776 is 677167166.

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 661761776.

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 7 ways as a sum of consecutive naturals, for example, 315740 + ... + 317828.

It is an arithmetic number, because the mean of its divisors is an integer number (34558986).

Almost surely, 2^661761776 is an apocalyptic number.

It is an amenable number.

661761776 is an abundant number, since it is smaller than the sum of its proper divisors (720597664).

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

661761776 is a wasteful number, since it uses less digits than its factorization.

661761776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3633 (or 3627 counting only the distinct ones).

The product of its digits is 444528, while the sum is 47.

The square root of 661761776 is about 25724.7308246364. The cubic root of 661761776 is about 871.4327806812.

The spelling of 661761776 in words is "six hundred sixty-one million, seven hundred sixty-one thousand, seven hundred seventy-six".