661221332075880 has 48 divisors (see below), whose sum is σ = 2148969329247780. Its totient is φ = 176325688553472.

The previous prime is 661221332075737. The next prime is 661221332075897. The reversal of 661221332075880 is 88570233122166.

661221332075880 is a `hidden beast` number, since 6 + 6 + 1 + 2 + 2 + 1 + 33 + 20 + 7 + 588 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 606108258378756 + 55113073697124 = 24619266^2 + 7423818^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 918362960857 + ... + 918362961576.

Almost surely, 2^{661221332075880} is an apocalyptic number.

661221332075880 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661221332075880 is an abundant number, since it is smaller than the sum of its proper divisors (1487747997171900).

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

661221332075880 is a wasteful number, since it uses less digits than its factorization.

661221332075880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1836725922450 (or 1836725922443 counting only the distinct ones).

The product of its (nonzero) digits is 5806080, while the sum is 54.

The spelling of 661221332075880 in words is "six hundred sixty-one trillion, two hundred twenty-one billion, three hundred thirty-two million, seventy-five thousand, eight hundred eighty".