661947410817 has 288 divisors, whose sum is σ = 1291982275584. Its totient is φ = 334773129600.

The previous prime is 661947410801. The next prime is 661947410827. The reversal of 661947410817 is 718014749166.

661947410817 is a `hidden beast` number, since 6 + 61 + 9 + 474 + 108 + 1 + 7 = 666.

It is not a de Polignac number, because 661947410817 - 2⁴ = 661947410801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661947410827) 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 287 ways as a sum of consecutive naturals, for example, 1159277142 + ... + 1159277712.

It is an arithmetic number, because the mean of its divisors is an integer number (4486049568).

Almost surely, 2^661947410817 is an apocalyptic number.

It is an amenable number.

661947410817 is a deficient number, since it is larger than the sum of its proper divisors (630034864767).

661947410817 is a wasteful number, since it uses less digits than its factorization.

661947410817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 831 (or 812 counting only the distinct ones).

The product of its (nonzero) digits is 2032128, while the sum is 54.

The spelling of 661947410817 in words is "six hundred sixty-one billion, nine hundred forty-seven million, four hundred ten thousand, eight hundred seventeen".