661778949888 has 108 divisors (see below), whose sum is σ = 2180653606768. Its totient is φ = 189079695360.

The previous prime is 661778949863. The next prime is 661778949973. The reversal of 661778949888 is 888949877166.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20500333 + ... + 20532588.

Almost surely, 2^661778949888 is an apocalyptic number.

It is an amenable number.

661778949888 is an abundant number, since it is smaller than the sum of its proper divisors (1518874656880).

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

661778949888 is a wasteful number, since it uses less digits than its factorization.

661778949888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41032950 (or 41032933 counting only the distinct ones).

The product of its digits is 2341011456, while the sum is 81.

The spelling of 661778949888 in words is "six hundred sixty-one billion, seven hundred seventy-eight million, nine hundred forty-nine thousand, eight hundred eighty-eight".