661515650505 has 24 divisors (see below), whose sum is σ = 1177617052872. Its totient is φ = 343272985344.

The previous prime is 661515650489. The next prime is 661515650507. The reversal of 661515650505 is 505056515166.

661515650505 is a `hidden beast` number, since 66 + 15 + 15 + 65 + 0 + 505 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 353520619776 + 307995030729 = 594576^2 + 554973^2 .

It is not a de Polignac number, because 661515650505 - 2⁴ = 661515650489 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (661515650507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 198651684 + ... + 198655013.

It is an arithmetic number, because the mean of its divisors is an integer number (49067377203).

Almost surely, 2^661515650505 is an apocalyptic number.

It is an amenable number.

661515650505 is a deficient number, since it is larger than the sum of its proper divisors (516101402367).

661515650505 is a wasteful number, since it uses less digits than its factorization.

661515650505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397306745 (or 397306742 counting only the distinct ones).

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

The spelling of 661515650505 in words is "six hundred sixty-one billion, five hundred fifteen million, six hundred fifty thousand, five hundred five".