661555505512 has 96 divisors (see below), whose sum is σ = 1445475031560. Its totient is φ = 282657689600.

The previous prime is 661555505477. The next prime is 661555505531. The reversal of 661555505512 is 215505555166.

661555505512 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 660556060516 + 999444996 = 812746^2 + 31614^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13090212 + ... + 13140652.

Almost surely, 2^661555505512 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 661555505512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (722737515780).

661555505512 is an abundant number, since it is smaller than the sum of its proper divisors (783919526048).

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

661555505512 is a wasteful number, since it uses less digits than its factorization.

661555505512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51283 (or 51268 counting only the distinct ones).

The product of its (nonzero) digits is 1125000, while the sum is 46.

The spelling of 661555505512 in words is "six hundred sixty-one billion, five hundred fifty-five million, five hundred five thousand, five hundred twelve".