661560155505 has 48 divisors (see below), whose sum is σ = 1237066169040. Its totient is φ = 325811625984.

The previous prime is 661560155497. The next prime is 661560155551. The reversal of 661560155505 is 505551065166.

661560155505 is a `hidden beast` number, since 66 + 15 + 60 + 15 + 5 + 505 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 1644383601 + 659915771904 = 40551^2 + 812352^2 .

It is not a de Polignac number, because 661560155505 - 2³ = 661560155497 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8117800 + ... + 8198889.

It is an arithmetic number, because the mean of its divisors is an integer number (25772211855).

Almost surely, 2^661560155505 is an apocalyptic number.

It is an amenable number.

661560155505 is a deficient number, since it is larger than the sum of its proper divisors (575506013535).

661560155505 is a wasteful number, since it uses less digits than its factorization.

661560155505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16316770 (or 16316767 counting only the distinct ones).

The product of its (nonzero) digits is 675000, while the sum is 45.

The spelling of 661560155505 in words is "six hundred sixty-one billion, five hundred sixty million, one hundred fifty-five thousand, five hundred five".